Mouse spermatogenesis genes, human male sterility-associated genes and diagnostic system using the same

ABSTRACT

The present invention provides a group of mouse spermatogenesis genes, which is an assembly of 89 genes in total, wherein the respective genes transcribe mRNAs from which cDNAs having the respective base sequences of SEQ ID NOs:1 to 89 are synthesized; an Scot-t gene mutation and a protamine-2 gene mutation which are human homologues of genes belonging to the group of mouse genes and associated with human male infertility. The invention also provides a group of mouse spermatogenesis genes and various molecular biological materials relating thereto; various molecular biological materials relating to male infertility-associated gene mutations; and various test methods and diagnostic methods using the same.

TECHNICAL FIELD

The invention of this application relates to an assembly (a group of genes: MSGs) of genes involved in mouse spermatogenesis (mouse spermatogenesis genes: hereinafter sometimes referred to as “MSG”) and a diagnostic system using the MSGs. More specifically, the invention relates to respective methods, e.g., toxicity test, mutagenicity test, and genetic diagnosis, which comprise detecting expression modulation, mutation, replacement of amino acid(s), and the like of MSG using respective genes and gene materials (purified polynucleotides, polypeptides as gene expression products, antibodies, etc.). The methods of the invention can be employed as a mutagenicity test and toxicity test (inclusive of a test relating to influence on reproduction) of medicaments and chemicals or as means for detection or environmental measurement of environmental hormones or endocrine disruptors and environmental assessment. Furthermore, the genes and genetic materials of the invention and respective method inventions contribute development of medical technologies on diagnosis, therapy and prevention of male infertility and development of diagnostic agents, therapeutic medicines or preventive medicines therefor, or contraceptive medicines.

Moreover, the invention of the application relates to methods for diagnosing male infertility wherein mutation or expression change of human male infertility-associated genes which are human homologues of mouse genes contained in the above MSGs; and wherein such a gene polymorphism as test targets. More specifically, the invention relates to methods for diagnosing male infertility wherein mutant polynucleotides derived from male infertility-associated genes characterized by point mutation or gene polymorphism, mutant polypeptides as the gene products thereof, and methods for diagnosing male infertility wherein these mutant polynucleotides and mutant polypeptides are used as targets. Moreover, similarly to the case of the above mouse MSG, the gene materials based on the information obtained from human homologues contribute to the development of medical technologies on diagnosis, therapy and prevention of male infertility and development of diagnostic agents, therapeutic medicines, preventive medicines, or contraceptive medicines there of.

BACKGROUND ART

Mouse Spermatogenesis Genes

Since proposal of the concept of endocrine disruptors (hereinafter sometimes referred to as “ED”) (1997), the risk of a low sperm count and impaired reproductive function to be induced by the ED has widely been well known, a sense of fateful crisis of human being has been raised and also global environmental conservation measures by development of MSDS (material safety data sheet) and PRTR (pollutant release and transfer registers) have been accelerated, so that development of methods for detecting and measuring ED and confirmation of influence of ED on living organisms become urgent problems. Furthermore, the conventional test for “influence on reproduction” with regard to medicaments, chemical agents, chemical products, chemical substances, and the like is a test only for teratogenicity as a measure. However, in order to avoid and sweep away the risk of impaired reproductive function to be induced by the ED, it is defective and insufficient to carry out the conventional teratogenicity test alone; therefore it is necessary to add detection of “mutagenicity for spermatogenesis genes of mammalians or human homologous genes thereof” or test for influence on spermatoblasts and processes of their differentiation and spermatogenesis (e.g., toxicity test or assay using expression modulation, mutation, amino acid replacement, or the like of MSG in a mouse testis or in vitro as a measure), to the toxicity test including a test for “influence on reproduction”. Thus, it is considered that the detection or test is considered to be a compelling problem to be necessarily solved.

However, heretofore, there are not known technologies on the toxicity test using expression modulation or mutation of spermatogenesis genes as a measure (test for influence on reproduction), the mutagenicity test, ED detection, and the like. The reason is that spermatogenesis genes usable as test targets are not identified.

Moreover, Western developed countries including Japan, it is known that about 10% of total married couple have experienced some forms of infertility problems and there is a possibility that about a half of them is attributed to factors at the male side. Part of the causes of male infertility suggested includes endocrine disorders, genetic factors including chromosomal abnormalities, environmental factors, anomalies including enorchima and varicocele (Rubio C, et al. Human Reprod 2001; 10: 2084-2092; Lee P A, et al. (2000) J Urol., 164(5), 1697-1701). However, most of the causes of male infertility are insufficient spermatogenesis and aspermatogenesis and the causes of the problems are not elucidated yet at present (Cram D S, et al. (2001) J Androl 22(5), 738-746). Moreover, among the cases of male infertility, there exist cases considered to be associated with various inherited factors (Thielemans B F J, et al. Eur. J. Obst Gynec 1998; 81: 217-225), but causative genes thereof are not always identified. Therefore, establishment of methods for diagnosing, treating, or preventing male infertility (e.g., genetic diagnosis and achievement of genetic therapy, drug treatment, and prevention based on a result of such a diagnosis) is a long-awaited problem to be solved, which provides significant good news for human being. Furthermore, when it is called to mind that high rates of birth may be accompanied by poverty, starvation and malnutrition, spread of infectious diseases such as AIDS, and the like in developing countries, development of contraceptives is also considered to be an important problem.

As mentioned above, in order to achieve effective detection of ED and the like by toxicity test or mutagenicity test, or to diagnose male infertility more reliablely, a molecular biological approach targeting spermatogenesis genes is indispensable. However, heretofore, any spermatogenesis gene (group) usable in such tests has not been identified and, as a matter of course, there is no proposal of means for applying such a gene (group) to various tests.

The invention of this application is accomplished in consideration of the above circumstances and an object thereof is to provide mouse spermatogenesis genes (MSGs) usable in the toxicity test, the mutagenicity test, or genetic diagnosis relating to ED detection and the like, and purified polynucleotides, polypeptides, antibodies, and the like as materials for carrying out such tests.

Also, another object of the invention is to provide respective methods for toxicity test, mutagenicity test, and genetic diagnosis using MSGs.

Mutation of Human Male Infertility-Associated Genes

As a result of extensive investigations of the relation between human homologues of mouse genes belonging to MSGs and male infertility, the inventors of this application have found that specific mutation in human Scot-t gene and protamine genes is involved in male infertility. In this regard, with regard to the relation between Scot-t gene and protamine genes and male infertility, the following have been known.

Succinyl CoA:3-oxo acid CoA transferase (OXCT/SCOT) is one of important enzymes in the energy metabolism of a ketone body and the ketone body is produced in the lever and transported to peripheral tissues to be used as an energy source (Mitchell G A, et al. Clin. Invest. Med. 1995; 18: 193-216). Succinyl CoA transferase (SCOT) is localized in a mitochondria of some tissues and catalyzes formation of acetoacetyl CoA by transferring the CoA moiety from succinyl CoA to acetoacetic acid. The acetoacetyl CoA is further decomposed into two acetyl CoA molecules capable of entering tricarboxylic acid cycle (Williamson, D. H. et al. (1971) Biochem. J., 121, 41-47; Tildon J T et al. J Clinic Invest 1972; 51: 493-498). Although cDNA of Scot has been cloned from swine and human heart (Lin, T. W. and Bridger W. A. (1992) J. Biol. Chem., 267, 975-978; Kassovska-Bratinova S, et al. Am J Hum Genet 1996; 59: 519-528), the inventors of this application has hitherto been cloned a novel gene named scot-t encoding haploid germ cell-specific SCOT from a differential cDNA library of mouse testis (Koga M, et al. Biol. Reprod 2000; 63: 1601-1609). The SCOT-t is an iso-form of SCOT specific to germ cells, is present in haploid sperm and sperm mitochondria, and is considered to play a specific role also in spermatogenesis and energy metabolism of sperm. According to Northern blotting, Western blotting, and immunohistochemical analysis, expression of mouse scot-t is detected in testis, especially in late spermatid, but is not detected in the other somatic cells. The nucleotide sequence of mouse scot-t has homology of 63.4% and 62.7% to Scot of swine and human hearts, respectively and presumed amino acid sequence has homology of 68.0% and 67.4%, respectively. One to 39 residues at NH₂ terminal of SCOT-t form a signal sequence targeting mitochondria. Actually in immunofluorescent stain, localization of SCOT-t protein in mitochondria in immobilized sperm obtained from tail of epididymis is shown (Koga M, et al. Biol Reprod 2000; 63: 1601-1609). The amino acid sequence of SCOT-t contains one glutamic acid residue (the amino acid residue in position of 341th), which corresponds to glutamic acid 344 which is known to be conserved in all CoA transferases including SCOT (Rochet J C, Bridger W A, (1994) Protein Sci., 3, 975-81). The inventors of this application have also cloned and characterized human orthologue of mouse scot-t. Whole coding region of mRNA of human Scot-t and deduced amino acid sequence show homology of 75.4% and 75.8% relative to those of mouse scot-t, respectively. Similarly, the inventors have indicated that h-Scot-t is a single gene having no introns and is expressed specifically in testis (Tanaka H, et al. Mol Human Reprod 2001; 8: 16-23).

There are some reports on importance of mitochondrial enzymes in energy metabolism in motility and functions of sperm (Pascual, M. I., et al. (1996) Biosci. Rep., 16, 35-40; Yeung, C. H., et al. (1996) Mol. Hum. Reprod., 2, 591-596; Ruiz-Pesini, E. et al. (1998) Clin. Chem., 44, 1616-1620). The fact that Scot-t is specifically present is considered to show the presence of a novel metabolic system wherein a ketone body is utilized as an energy source for sperm motion. Furthermore, since Scot-t is specifically expressed in haploid spermatids, it is suggested that Scot-t may play some specific role in spermatogenesis.

Moreover, a remarkable reorganization in sperm nuclei occurs at a spermatogenesis stage. In this process, histone is removed and the nuclei undergo replacement by a specific nuclear protein and finally replaced by protamine having a high positive charge, whereby it is highly compressed (Wounters-Tyrou, D. et al. (1998) Biochimie, 80, 117-128; Sassone-Corsi P. (2002) Science, 296, 2176-2178). DNAs of human sperm are assembled in head of sperm in a highly condensed state by two kinds of protamines, i.e., protamine-1 and protamine-2. Protamine-1 is a single polypeptide molecule having 50 amino acids, on the other hand, protamine-2 is a complex of at least two different forms having 57 and 54 amino acids (Mckay, D. J. et al. (1986) Eur. J. Biochem., 158, 361-366). Protamine-2 family proteins are synthesized as precursors having 66 to 101 residues based on a single copy gene present in the 16th chromosome (Krawetz, S. A. et al. (1989) Genomics. 5, 639-645; Reeves, R. H. et al. (1989) J. Hered, 80, 442-446).

It is suggested that male infertility occurs as a result of the nuclear concentration disorder. In mouse, as a result of early translation of mRNA of protamine-1, immature nuclear concentration occurs to terminate differentiation of sperm (Lee, K. et al. (1995) Proc. Nat.l. Acad. Sci. USA, 92, 12451-12455). In various studies targeting infertile patients, decrease of content of protamine-2 has been reported (Balhorn, R. et al. (1988) Experientia., 44, 52-55; Belokopytova, J. A. et al. (1993) Mol. Reprod. Dev., 34, 53-57), and there is a report that completely selective protamine-2 deficit is observed in sperm nuclei of part of male infertile patients (de Yaba, L. et al. (1993) J. Biol. Chem., 268: 10553-10557). However, in the results of sequence analysis of protamine-2 gene obtained from these patients, the presence of mutation causing the detected decrease of protamine-2 is not observed (de Yaba, L. et al. (1993) J. Biol. Chem., 268: 10553-10557; Schlicker, M. et al. (1994) Hum Reprod., 9, 2313-2317). Moreover, it is suggested that decrease of protamine-2 occurs owing to incomplete processing of protamine-2 precursor molecules in part of infertile patients (d Yebra, L. et al. (1998) Fertil Steril., 69, 755-759).

As mentioned above, it is pointed out that some mutation of Scot-t gene or protamine gene may be associated with male infertility but the reality of the situation is not at all elucidated. An object of the invention of this application is to provide Scot-t gene mutation and protamine-2 gene mutation as causal genes of human male infertility.

Also, another object of the invention is to provide a mutant polypeptide expressed with the above gene mutation, an antibody against the mutant polypeptide, and a method for diagnosing male infertility using these mutant gene and mutant polypeptide as test targets.

DISCLOSURE OF INVENTION

This application provides the following mouse spermatogenesis gene group and inventions utilizing the same as inventions for achieving the above objects.

Namely, the invention provides a group of mouse spermatogenesis genes, which is an assembly of 89 genes in total, wherein the respective genes transcribe mRNAs from which cDNAs having the respective base sequences of SEQ ID NOs:1 to 89 are synthesized.

The invention provides a cDNA library, which consists of cDNAs derived from the respective genes belonging to said group of mouse spermatogenesis genes.

The invention provides a group of DNA fragments each consisting of the base sequence of continuous 10 to 99 bases of the respective cDNAs belonging to said group of cDNA library.

The invention provides a group of primer sets for PCR amplification of DNAs of the respective genes belonging to said group of mouse spermatogenesis genes or the respective cDNAs belonging to said group of cDNAs.

The invention provides a microarray comprising one or more cDNAs belonging to said group of cDNAs or one or more DNA fragments belonging to said group of DNA fragments.

The invention provides a group of mouse spermatogenesis polypeptides, which is an assembly of 78 polypeptides in total, wherein the respective peptides have the respective amino acid sequences of SEQ ID NOs:90 to 167.

The invention provides a group of antibodies against the respective polypeptides belonging to said group of mouse spermatogenesis polypeptides.

The invention further provides a method for assaying toxicity or mutagenicity of a subject substance, which comprising detecting expression modulation or mutation of one or more genes belonging to said group of mouse spermatogenesis genes.

Furthermore, the invention provides a method for diagnosing reproductive ability of a subject individual, which comprises detecting expression modulation or mutation of one or more genes belonging to said group of mouse spermatogenesis genes.

Namely, the MSGs of the above invention is cloned by the following three kinds of methods based on the concept that “detection of expression modulation and mutation of spermatogenesis genes can be utilized to a toxicity test, especially a reproductive toxicity test and a mutagenicity test”.

(a) Cloning Using Monoclonal Antibody

A monoclonal antibody specifically recognizing each processes of spermatogenesis was prepared and an objective gene (group) was identified. Namely, a cell extraction fraction was obtained from mouse testis and rats were immunized therewith. After thorough immunization, the obtained spleen cells were subjected to cell fusion with myeloma cells to prepare hybridomas. In order to search for a hybridoma which prepares an antibody specifically recognizing spermatoblast from the obtained respective hybridomas, the hybridomas were screened by reacting them with slices of the testis and investigating what kinds of antigens were recognized by antibodies produced in culture supernatants of respective hybridomas, whereby hybridomas producing spermatoblast-specific antibodies were obtained. Using the obtained monoclonal antibody, genes encoding antigen proteins recognized by the antibodies were cloned from a mouse testis library expressed in Escherichia coli.

(b) Cloning Using Polyclonal Antibody

A polyclonal antibody specifically recognizing spermatoblasts (inclusive of cells at all differentiation stage) was prepared and an objective gene (group) was identified. Namely, a spermatoblast extract fraction was obtained from mouse testis and rabbits were thoroughly immunized therewith. The obtained serum was injected into abdominal cavity of a castrated male mouse and antibodies recognizing cells other than spermatoblast were absorbed. A serum content of the mouse was collected and further reacted with a liver extraction fraction. Antigen genes recognized by the rabbit antibodies contained in the obtained serum were cloned from a mouse testis library expressed in Escherichia coli.

(c) Cloning Using Subtracted Library

A subtracted library containing a concentrated gene group specific to spermatoblasts was prepared and a gene group specifically expressed at each differentiation stage was cloned, followed by analysis of functions of each resulting clone. In particular, spermatid is a sole haploid cell which is present in an animal individual in a large number for a long period of time. Since the genes of the group specifically expressed in such spermatid each exhibits a specific function for spermatogenesis, these genes of the group were comprehensively cloned and phenomena specific to spermatogenesis were analyzed. Specifically, a subtracted library was obtained wherein mRNAs expressed in testis of a 17 day-old mouse having no spermatid were subtracted from a cDNA library of testis of 35 day-old mouse (C57BL/6) having spermatoblasts at all differentiation stages was prepared. From the subtracted library, a gene group specifically expressed at a morphogenesis stage of spermatid.

By the above methods (a) to (c), 89 clones in total of spermatoblast-specific gene cDNAs (MSGs cDNAs) were obtained. Then, basic sequences of respective cDNA clones were determined according to a known method, and it was confirmed that these cDNAs were composed of basic sequences shown in odd number sequences of SEQ ID NOS:1 to 89. Moreover, homology search thereof was carried out among various base sequences already reported and it was found that, in 89 of the MSG clone, known genes were about 26%, homologous genes were 32%, and especially, unknown gene were up to 42%.

Table 1 shows, from left to right, “Sequence Number”, “Name of Gene” (known one), “Database (GenBank) Registry Number”, “Sequence Number of Polypeptide” encoded by the gene, and “Coding Region” thereof, of 89 genes in total shown in SEQ ID NOS: 1 to 89. TABLE 1 1 AKAP110 AF093406 90  292-2884 2 unidentified 3 Rbcc728 (human), Trim36 (human) 91  45-2202 4 Nopp140 (rat) 92 401- 5 93  1-302 6 94  12-573 7 95 109-889 8 96 543-861 9 unidentified 10 97  1-372 11 98  1-319 12 ATR AF236887.1 99 168-606 13 100 396-546 14 HSpb (mouse) unidentified 15 unidentified 16 Spergen-1 (rat) AB047508 101  66-513 17 102  140-1445 18 103 1046-1994 19 104  362-1127 20 arylsulfatase A X73230 105  642-2160 21 106 111- 22 107  1-202 23 108  47-550 24 Drctnnbla 109 228-768 25 110  1-420 26 unidentified 27 111  1-278 28 112  334-2719 29 unidentified 30 113 165-462 31 114 242-695 32 unidentified 33 unidentified 34 CDC14B (human) 115  1-534 35 unidentified 36 cystatin-related epididymal spermatogenic AF090691 116 180-606 protein 37 unidentified 38 117 511-868 39 118  1-619 40 pregnancy-induced growth inhibitor AY037158.1 119 287-698 (human) 41 unidentified 42 120, 160-550, 121 618-957 43 fatty acid coenzyme A ligase, long chain 2 NM_007981 122   1-2098 44 Fem NM_010193 123  75-1956 45 major 80,000 Mr fibrous sheath component U10341 124  121-2668 46 125  14-566 47 126  46-655 48 Glycerol phosphate dehydrogenase 1, NM_010274 127  131-2312 mitochondrial 49 Lim domains containing 1 NM_013860 128  527-2531 50 oaz-t AB016275 129 193-788 51 pctp-1 AB031550 130  325-1198 52 testis-specific phosphoglycerate kinase M18654 131  21-1272 53 phospholipase C delta 4 AF125974 132 26- 54 protamine 1 X07625 133  1-145 55 protamine 2 NM_008933 134  82-388 56 scot-t1 AB022180 135  32-1592 57 scot-t2 AB049996 136  32-1592 58 mitochondrial capsule selenoprotein NM_008574 137 190-819 59 SP-56 U17108 138  80-181 60 Sperizin AB016984 139  113-1093 61 oppo 1 AB074438 140  83-917 62 Gal beta-1, 3-GalNAc-specific GalNAc X93999 141  67-1186 alpha-2, 6-sialyltransferase 63 suppressor of fused homolog (Drosophila) NM_015752 142  148-1603 64 t-actin 1 AB023062 143  28-1282 65 t-actin 2 AB023063 144  64-1384 66 t-complex Tcp-10a X58170 145  897-2211 67 tektin-t AB027138 146  117-1407 68 teek 1 NM_009355 147  28-1129 69 TP-2 M60254 148  61-412 70 tsec-1 AB000619 149  211-1252 71 tssk 1.2 substrate AF025310 150  25-1603 72 serine/threonine kinase 22B (spermiogenesis NM_009436 151  28-1099 associated) 73 SCP1 D88539 152 unidentified 74 tsga2 NM_025290 153  90-942 75 Gapd-S NM_008085 154  1-131 76 meichroacidin D88453 155  90-941 77 halap-X AB032764 156  1-805 78 157  158-1082 79 Ssecks AF326230 158  457-5194 80 gsg1 NM_010352 159  144-1056 81 haspin NM_010353 160  34-2296 82 gsg3 NM_007605 161  111-1008 83 hils1 NM_018792 162 241-649 84 163  14-1208 85 164 292-973 86 shippo1 AB067773 165 121-883 87 putative lysophosphatidic acid acyltransferase NM_018743 166  78-534 88 167  1-292 89 unidentified

Furthermore, the following findings (1) to (4) were obtained in the above MSG clones group.

-   (1) With regard to the gene structure, most of 89 clones of MSG have     no intron and, even if intron is present, most of them have very     little one. -   (2) Most of them have no known transcription-related factor-binding     sequence such as TATA, CAAT, GC motif, and the like. -   (3) Expression timing is specific to the spermatogenesis stage. For     example, in the process of primordial germ     cell->spermatogonium->spermatocyte->spermatid     (haploid)->sperm->acquisition of reproductive ability in female     genital tract, there are a number of genes specifically expressing     only at the stage of spermatid->sperm. -   (4) With regard to actions and functions of expressed products,     there are observed those wherein an iso-form characteristic to germ     cell against somatic cells is present and which exhibits     considerably specific activity at respective stages of     spermatogenesis. For example, those exhibiting the action only in     the fertilization process are present.

Of these findings, the above (1) and (3) relating to intron are particularly important. Namely, the reasons are as follows: it is suggested that “the structures and transcription of the genes involved in spermatogenesis are (1) relatively simple and detection of mutation is not difficult and even when mutation occurs in the gene, the (3) expression occurs only in germ cells and the mutation character does not appear in somatic cells but appears only in germ cells to result in infertility” and it is judged that detection of the expression modulation and mutation is utilizable as a reproduction toxicity test and a mutagenicity test.

In this regard, part of the findings regarding Table 1 and the above MSGs are described in detail in the following literatures reported by the inventors of this application: Int. J. Androl. 20: 361-366, 1997; Gene 204: 159-163, 1997; Genomics 46: 138-142, 1997; Mammal. Genome 8: 873-874, 1997; Cytogenet. Cell Gent. 78: 103-104, 1997; Nature 387: 607-611, 1997; Dev. Biol. 197: 67-76, 1998; Biol. Reprod 58: 261-265, 1998; Gene 237: 193-199, 1999; J. Biol. Chem. 274: 17049-17057, 1999; FEBS Lett. 456: 315-321, 1999; Genomics 57: 94-101, 1999; Biol. Reprod. 62: 1694-1701, 2000; Biol. Reprod. 63: 993-999, 2000; Genes Cells 5: 265-276, 2000; Biol. Reprod. 63: 1601-1609, 2000; Gene 267: 49-54, 2001; Mol. Human Reprod. 7: 211-218, 2001.

Furthermore, this application provides an invention of mutation of a male infertility-associated genes among the genes contained in the above group of mouse spermatogenesis genes and inventions utilizing the genes' mutation.

Namely, the invention provides a polynucleotide (Scot-t mutant polynucleotide) or a complementary sequence thereof, which polynucleotide is complementary to mRNA transcribed from a human male infertility-associated gene Scot-t, and has one or more mutations selected from the following group:

-   -   “t” at 129th position is replaced by “c”;     -   “t” at 870th position is replaced by “g”;     -   “c” at 1071st position is replaced by “at”; and     -   “t” at 1667th position is replaced by “c”,         in the DNA sequence of SEQ ID NO:168.

The invention provides a Scot-t mutant oligonucleotide or a complementary sequence thereof, which is part of the above Scot-t mutant polynucleotide and is a DNA sequence consisting of continuous 10 to 99 bases containing the said mutation sites.

The invention provides a polynucleotide (Scot-t mutant genomic polynucleotide) derived from a human chromosomal DNA, which hybridizes the above Scot-t mutant polynucleotide or the above Scot-t mutant oligonucleotide or the complementary sequences thereof under a stringent condition.

The invention provides a primer set for PCR amplification of the above Scot-t mutant polynucleotide, the above Scot-t mutant genomic polynucleotide, or the mRNA transcribed from the Scot-t mutant genomic polynucleotide, wherein one of the primers is an oligonucleotide or a complementary sequence thereof which is a DNA sequence consisting of continuous 15 to 45 bases containing the mutation site.

The invention provides a polynucleotide (protamine-2 mutant polynucleotide) or a complementary sequence thereof, which polunucleotide is complementary to mRNA transcribed from a human male infertility-associated gene protamine-2, and “c” at 248th position is replaced by “t” in the DNA sequence of SEQ ID NO:173.

The invention provides an oligonucleotide (protamine-2 mutant oligonucleotide) a complementary sequence thereof, which is part of the protamine-2 mutant polynucleotide and is a DNA sequence consisting of continuous 10 to 99 bases containing the mutation site.

The invention provides a polynucleotide (protamine-2 mutant genomic polynucleotide) derived from a human chromosomal DNA, which hybridizes the protamine-2 mutant polynucleotide or the protamine-2 mutant oligonucleotide or the complementary sequences thereof under a stringent condition.

The invention provides a primer set for PCR amplification of the above protamine-2 mutant polynucleotide, the protamine-2 mutant genomic polynucleotide, or the mRNA transcribed from the protamine-2 mutant genomic polynucleotide, wherein one of the primers is an oligonucleotide or a complementary sequence thereof which is a DNA sequence consisting of continuous 15 to 45 bases containing the mutation site.

The invention provides a polypeptide (Scot-t mutant polypeptide), an expression product of the above Scot-t mutant polynucleotide or Scot-t mutant genomic polynucleotide, which has one or more mutations selected from the following group:

-   -   Leu at 38th position is replaced by Pro;     -   Leu at 285th position is replaced by Arg; and     -   Thr at 352nd position is replaced by Met,         in the amino acid sequence of SEQ ID NO:169.

The invention provides a polypeptide (protamine-2 mutant polypeptide), an expression product of the above protamine-2 mutant polynucleotide or protamine-2 mutant genomic polynucleotide, which consists of the amino acid sequence of 1st to 49th positions of the amino acid sequence of SEQ ID NO:174.

The invention provides an oligopeptide (Scot-t mutant oligopeptide), which is a part of the above Scot-t mutant polypeptide and is an amino acid sequence consisting of continuous 5 to 30 amino acids containing the mutation site.

The invention provides an oligopeptide (protamine-2 mutant polypeptide), which is a part of the protamine-2 mutant polypeptide and is an amino acid sequence consisting of continuous 5 to 30 amino acids.

The invention provides an antibody (anti-mutant Scot-t antibody) prepared using the above Scot-t mutant oligopeptide as an antigen, and an antibody (anti-mutant protamine-2 antibody) prepared using the above protamine-2 mutant oligopeptide as an antigen, respectively.

The invention provides an antibody (anti-protamine-2 antibody) prepared using the oligopeptide consisting of the amino acid sequence of 50th to 91st positions of SEQ ID NO:174 or an amino acid sequence of 1st to 11th positions of SEQ ID NO:175 as an antigen.

The invention also provides a method for diagnosing male infertility, which comprises detecting presence of the Scot-t mutant genomic polynucleotide or protamine-2 mutant genomic polynucleotide in a chromosomal DNA isolated from a subject person.

In the above diagnostic method, a preferred embodiment comprises detecting whether a chromosomal DNA or an mRNA thereof isolated from a subject person hybridizes the Scot-t mutant polypeptide or protamine-2 mutant polynucleotide or the Scot-t mutant oligonucleotide or protamine-2 mutant oligonucleotide, or a complimentary sequence thereof under a stringent condition or not. Moreover, in the diagnostic method, another preferred embodiment comprises detecting presence of a PCR product when PCR is carried out using a chromosomal DNA or mRNA isolated from a subject person as a template with the respective primer sets.

The invention provides a method for diagnosing male infertility, which comprises detecting presence of the Scot-t mutant polypeptide or protamine-2 mutant polypeptide in a biological sample isolated from a subject person.

In the above diagnostic method, a preferred embodiment comprises detecting presence of a polypeptide reactive to the anti-mutant Scot-t antibody in a biological sample isolated from a subject person. Moreover, in the diagnostic method, another preferred embodiment comprises detecting presence of a polypeptide reactive to the anti-mutant protamine-2 antibody but not reactive to the anti-protamine-2 antibody in a biological sample isolated from a subject person.

The invention provides a DNA probe, which is labeled Scot-t mutant oligonucleotide or labeled protamine-2 mutant oligonucleotide.

The invention provides a DNA chip comprising the above Scot-t mutant oligonucleotide and/or protamine-2 mutant oligonucleotide.

The invention provides a labeled antibody, wherein the above anti-mutant Scot-t antibody, anti-mutant protamine-2 antibody, or anti-protamine-2 antibody is labeled.

Namely, as a result of analysis on DNA samples of 516 male persons (infertility: 255 cases, healthy persons: 261 cases) for Scot-t gene and 496 male persons (infertility: 226 cases, healthy persons: 270 cases) for protamine genes, the inventors of this application have found that nucleotide mutations and resulting amino acid mutations as shown in Table 2 are present in each cDNA (Scot-t: SEQ ID NO:168, protamine-1: SEQ ID NO:170, protamine-2: SEQ ID NO:173). They have found that one base replacement and amino acid mutation in Scot-t and a shortened protein caused by one base replacement in protamine-2 are particularly important as a cause of male infertility. In this regard, SEQ ID NO:168 corresponds to the base sequence of 4th to 1760th in known human Scot-t cDNA (GenBank/AB050193). SEQ ID NO:170 corresponds to the base sequence of 532-1089 in known human protamine-1 cDNA (GenBank/M60331). Moreover, SEQ ID NO:173 corresponds to a base sequence of 804-1629 in known human protamine-2 cDNA (GenBank/M60332). The positions of nucleotide mutations and amino acid mutations in Table 2 correspond to the base positions and amino acid positions in the sequence tables. Moreover, the sign of “-” means a non-coding region, “silent” means that the amino acid does not mutate with the nucleotide mutation, and the mark of “***” means mutation into a stop codon. In addition, “deletion” means deletion of a nucleotide and “addition” means addition of a nucleotide. TABLE 2 Nucleotide Mutation Amino Acid Mutation Scot-t t129c Leu38Pro t870g Leu285Arg c1071t Thr352Met t1667c — Protamine-1 c44: eletion — g73: addition — a133g (silent) c160a (silent) g363a (silent) c364a (silent) a431g — Protamine-2 c248t Glu50*** g398c or a — a473c — t493: deletion —

In each invention of this application, a “gene” is present in a genomic DNA and is a double-stranded DNA encoding a specific polypeptide (protein), and it contains a coding region (open reading flame: ORF) and expression-regulating region(s) (promoter/enhancer sequence, repressor sequence) according to the ORF.

In the invention of this application, the “polynucleotide” and “oligonucleotide” mean long-chain or single-chain nucleotide chains, respectively. A tentative criteria are that the polynucleotide contains 100 bp or more and oligonucleotide contains less than 100 bp, but there exist some exceptions.

In the invention, the “polypeptide” and “oligopeptide” mean long-chain or single-chain peptide chains, respectively. A tentative criteria are that the polypeptide contains 30 amino acids or more and oligopeptide contains less than 30 amino acids, but there exist some exceptions.

Moreover, in the following explanation, “influence on reproduction” means not teratogenicity but influence on spermatogenesis and fertility.

Furthermore, the other terms and concepts used in the invention may be explained in the description of Mode for Carrying Out the Invention and Examples. In this regard, various gene manipulating technologies and molecular biological technologies used for carrying out the invention are easily and surely practicable for those skilled in the art based on known literatures (e.g., Sambrook and Maniatis, in Molecular Cloning—A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York, 1989; Ausubel, F. M. et al., Current Protocols in Molecular Biology, John Wiley & Sons, New York, N.Y., 1995, etc.) except for the technologies for which their sources are particularly indicated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration demonstrating human Scot-t genomic DNA and protein together with SNPs positions. Horizontal arrows show two pairs of primers.

FIG. 2 shows a genomic DNA sequence of protamine-1 and primers for PCR amplification and sequence analysis. Translation starting point, intron, and canonical poly A addition signal are shown by +1, an outline box, and shadowed characters, respectively. The primer sequences are underlined parts. The amino acid sequence of each protein is written with capital letters under the nucleotide sequence. Numerals in right margin show position numbers of nucleotide and amino acid (thick letters) sequences (the nucleotide position number is a number from the translation starting point (+1) and note that it is different from SEQ ID NO:170). SNPs are shown by thick letters. Asterisk shows difference of nucleotides possessed by 496 cases of human male patients of parent population in which infertility and reproduction ability are proved, from GenBank registered sequence (EMBL/DDBJ/GenBank/Y00443, M29706, M60331, M60332).

FIG. 3 shows, just as FIG. 2 shows, a genomic DNA sequence of protamine-2 and primers for PCR amplification and sequence analysis.

BEST MODE FOR CARRYING OUT THE INVENTION

The mouse spermatogenesis genes group (MSGs) is an assembly of 89 genes in total wherein cDNAs synthesized from mRNAs transcribed from the respective genes have the base sequences represented by SEQ ID NOS:1 to 89.

cDNAs can be identified by cloning methods of (a) to (c) as mentioned above or a combination thereof. These methods are all known methods and can be carried out by those skilled in the art without requiring undue experiment. For example, basic procedure of operations of the subtraction method in the method (c) is exemplified in general textbooks (Current Protocol in Molecular Biology 1:5.8.9-5.9.20, Green Publishing Associate and Willey-Interscience, 1987-). Namely, (i) after total RNAs and mRNAs are extracted from testis of mature mouse having spermatoblasts at all differential stages, e.g., 35 day-old mouse and purified, cDNAs corresponding to mRNAs are synthesized to prepare a cDNA library, and separately (ii) total RNAs and mRNAs are extracted from testis of immature mouse having undifferentiated spermatoblasts, for example, 17 day-old mouse and purified and the mRNAs are, for example, labeled with biotin. Then, (iii) hybridization is carried out between the above cDNA library and excess concentration of the biotin-labeled mRNAs, and hybrids formed from these both substances and remaining excess biotin-labeled mRNAs are removed by agglomeration with avidin to prepare a subtracted cDNA library. Thereafter, (iv) from the above subtracted cDNA library, for example, by Northern blotting using total RNAs of both 17 day-old and 35 day-old mice, cDNAs specifically reactive to the total RNAs of 35 day-old mouse are selected and collected (cloned) and thereby MSG clones can be obtained. In this regard, when the above cDNA library and subtracted cDNA library are formed in a form of the resulting transformants by inserting and linking the cDNAs to a vector and transferring it into a host Escherichia coli, subsequent amplification, preparation, and screening of the cDNAs are all facilitated.

The MSGs of the invention can also be defined as genomic DNA fragments which hybridize oligonucleotide probes synthesized based on the base sequence information of cDNA clones (SEQ ID NOS:1 to 89) identified by the above methods. Hybridization is carried out under “stringent conditions” wherein salt concentration, organic solvent concentration, and temperature, and the like are within certain ranges.

Thus identified gene DNA (genomic DNA) of the MSGs can be isolated by screening the mouse genomic DNA library which is cloned to a BAC (Bacterial Artificial Chromosome) vector, a cosmid vector, a phage vector, or the like, using the above probes. The isolated genomic DNA fragments can be also used as probes, for example, for diagnosing chromosome aberration by fluorescent in situ hybridization (FISH).

Moreover, determination of base sequence of the obtained MSGs clone cDNAs can be conducted by a known method and is usually conducted by a cycle sequence method (Current Protocol in Molecular Biology, 1: 7.4A. 12-7.4A. 13) using dideoxy method (Sanger method) as an elementary method. An advantage of the cycle sequence method is that a polynucleotide obtained from PCR amplification can be directly sequenced, which can be achieved using a commercially available Thermo Sequenase fluorescent labelled primer cycle sequencing kit [manufactured by Amasham (USA)] and a LC4000 autosequencer [manufactured by LI-COR].

In this regard, polynucleotides (DNA fragments and RNA fragments) can be also purified by known methods from genomic DNAs or mRNAs of respective genes belonging to MSGs. Such purified polynucleotides are useful, for example, as targets to be tested in the toxicity test and the like.

Furthermore, these polynucleotides and the above cDNAs can be used for detection and cloning of homogeneous genes. Namely, for example, homology search using the base sequences of SEQ ID NOS:1 to 89 enables detection of homologous genes of animals and plants other than mouse homologous to the MSGs, e.g., homologous base sequences in human genomic DNA. For the homology search, it is possible to use gene databases provided by, for example, DDBJ (http://www.ddjb.nig.ac.jp/), NCBI (http://www/ncbi.nim.nih.gov/), and the like. The homologous gene can be found in the form of a full-length base sequence, EST (expression sequence tags), STS (sequence tagged sites), GSS (genome survey sequence), SNP (single nucleotide polymorphism), or the like. Moreover, these homologous genes can be screened and cloned, for example, directly from human chromosomal DNAs (using DNAs extracted and prepared from chromosome of human sperm, leucocyte, etc.), or by hybridization using probes provided by the invention, RT-PCR with a PCR primer, or the like.

The DNA fragment group of the invention is an assembly of respective gene DNAs belonging to the above MSGs group or continuous 10 to 99 base fragments (sense chains or antisense chains) of respective cDNAs belonging to the above cDNA group. These DNA fragments are useful as probes in the hybridization assay for detecting mutation of gene MSGs, for example. Moreover, they can be used as probes for the reproduction toxicity test and preparation of a microarray for gene diagnosis of infertility.

These DNA fragments can be also prepared by synthesis in accordance with usual methods or optionally by cleavage of the above polynucleotides and cDNAs with appropriate restriction enzymes.

The primer set group of the invention is an assembly of synthetic oligonucleotides for PCR amplification of the above gene MSGs and cDNAs, and expression modulation and mutation of respective genes of MSGs can be detected by PCR using these primer sets.

These primer sets can be designed on the basis of the base sequences of SEQ ID NOS:1 to 89 and prepared via respective steps of synthesis and purification. In this regard, since success of PCR largely depends on the primer design and setting of various conditions, various ingenuity and trials are necessary to prepare an optimum primer. As points to keep in mind for the primer design, the following may be pointed out, for example. The size of primer (number of bases) is from 15 to 40 bases, preferably 15 to 30 bases in consideration of satisfying a specific annealing with a template DNA. However, in the case that LA (long accurate) PCR is carried out, the number is effectively at least 30 bases. In order to prevent annealing of one set of the sense chain (5-terminal side) and the antisense chain (3-terminal side) or one pair (two primers) of primers each other, use of a complementary sequence between two primers is avoided. Also, in order to prevent formation of hair-pin structure in the primers, it is tried to avoid use of self-complementary sequence. Furthermore, in order to assure a stable binding to the template DNA, GC content is made about 50% and localization of GC-rich or AT-rich may be avoided in the primers. Since annealing temperature depends on Tm (melting temperature), primers having a Tm value which is from 55 to 65° C. and which is close to each other is selected in order to obtain a PCR product having a high specificity. Moreover, it is necessary to take note so that the final concentration of the primer used in the PCR becomes from about 0.1 to about 1 μM. Furthermore, commercially available software for the primer design, for example, Oligo™ [manufactured by National Bioscience Inc., (USA)], GENETYX [manufactured by Software Development K.K. (Japan)], or the like may be employed. In this regard, the invention provides one or more sets of two oligonucleotides for PCR amplification of each cDNA in respective cDNA base sequences for SEQ ID NOS:1 to 89.

The microarray (DNA chip) of the invention is characterized in that the above cDNAs or one or more of continuous 10 to 99 base fragments of the cDNAs are provided as probes in a substrate. In this regard, two or more or five or more cDNAs are preferably provided. Such microarray may be a microarray wherein the DNA fragments are directly synthesized on the substrate or a microarray wherein the DNA fragments are spotted on the substrate coated with a material with which DNA can combine.

The spermatogenic polypeptide group of the invention can be obtained according to a method of isolation from mouse cells, a method of preparing peptides by chemical synthesis based on the amino acid sequences of SEQ ID NOS:90 to 167, or the like methods. In addition, the group can also be obtained in a large amount according to a genetic recombination method using polynucleotides such as cDNAs. Namely, polypeptides encoded by MSGs can be obtained in a large amount by inserting cDNA or an ORF region thereof into an expression vector for in vitro transcription or an expression vector suitable for prokaryotic cells such as Escherichia coli and Bacillus subtilis and eukaryotic cells such as yeasts, insect cells and mammalian cells, and by in vitro transcription or from transformant cells transformed with the expression vectors. The transformant cells can be produced by transferring the recombinant vectors into cells according to known methods such as electroporation, calcium phosphate method, ribosome method, and DEAE dextran method. Moreover, for isolation and purification of the polypeptides from culture products of the transformant cells, use can be made of known methods, for example, treatment with a denaturing agent such as urea or a surfactant, ultrasonic treatment, enzymatic digestion, salting-out or solvent precipitation method, dialysis, centrifugation, ultrafiltration, gel filtration, SDS-PAGE, isoelectric focusing electrophoresis, ion-exchange chromatography, hydrophobic chromatography, affinity chromatography, reverse phase chromatography, and the like. In this regard, the polypeptides of the invention include fused proteins with other any proteins. For example, fused proteins with glutathion-S-tansferase (GST), green fluorescent protein (GFP), or the like may be mentioned. Furthermore, proteins expressed in cells may sometimes undergo various modifications in the cells after translation. Accordingly, the modified proteins are also included in the invention. Such modifications after translation are elimination of N-terminal methionine, N-terminal acetylation, sugar-chain addition, limited degradation with an intracellular protease, myristoylation, isoprenylation, phosphorylation, and the like.

The thus obtained polypeptides are useful as immunogens for antibody preparation, target molecules for developing therapeutic agents for infertility, or the like.

The antibody group of the invention is an assembly of polyclonal antibodies or monoclonal antibodies which recognize the above MSGs polypeptides. The antibody group is useful as materials for carrying out the toxicity test and genetic diagnosis by investigating expression of MSGs polypeptides or mutants thereof in spermatoblast. The antibodies include all of the whole molecules capable of binding to epitopes of MSGs polypeptides, and Fab, F(ab′)₂, Fv fragments, and the like. For example, in the case of polyclonal antibodies, such antibodies can be obtained from sera of animals after immunization of the animals using the above MSGs polypeptide or its partial peptide. Alternatively, they can be prepared by collecting sera of animals after the above expression vectors are transferred into muscle or skin of the animals by injection or a gene gun. As the animals, mouse, rat, rabbit, goat, chicken, and the like are used. Preparation of hybridomas by fusing B cells collected from spleens of immunized animals with myelonas enables production of monoclonal antibodies.

The methods for toxicity test, mutagenicity test, and genetic diagnosis according to the invention can be carried out, for example, in accordance with the following (A) to (I).

(A) Detection of ED (In Vivo):

For example, using an experimental animal such as mouse, guinea pig, or monkey reared under administration of an ED-suspected substance, chromosomal DNA is extracted from the leukocytes, tissue cells, and the like and purified (above Current Protocol in Molecular Biology 1:2.2.1-2.2.3). Using the DNA, an experimental animal DNA homologous to MSGs is amplified by PCR with the above primer set to prepare an analyte DNA. The base sequence thereof is determined and homology search is carried out between the analyte and normal gene DNA. As a result of the search, genetic diagnosis wherein mutation in the experimental animal, expression modulation induced by the mutation, and amino acid replacement are analyzed can be carried out on the basis of the resulting difference in base sequence and amino acid sequence between both DNAs. For the search, use can be made of, for example, a commercially available software for homology search (a program for homology search provided by the above DDBJ or NCBI, e.g., FASTA, BLAST, PSI-BLAST, SSEARCH, etc.). In this regard, points to keep in mind for homology search are described in, for example, a literature (Current Protocol in Molecular Biology 1:7.7.12-7.7.15). Furthermore, using RNA extracted from each organ (especially testis and sperm) of the above animal, it can be judged whether the suspected substance is ED or not by detecting change in expressed amount of mRNA by Northern blotting, RT-PCR method, microarray method, or the like with regard to MSGs.

(B) Detection of ED (In Vitro):

For example, using cell culture wherein an ED suspected substance is added to and mixed with a medium and culture is effected, tetrahymena, echinus fertilized eggs, microorganisms, and the like, morphological anomaly (e.g., abnormal cell division, cellular degeneration, etc.) under the cultivation is detected on a microscope and also a gene DNA (analyte DNA) homologous to the MSGs is prepared from the above culture product as in the above (A), followed by homology search. Thus, by investigating occurrence of mutation and change of expressed amount by Northern blotting, RT-PCR method, or the like, it can be judged whether the suspected substance is ED or not. In this regard, as the culture cell, a transformant with an expression vector obtained by cloning each polynucleotide (cDNA) of the MSGs of the invention can be employed.

(C) Mutagenicity Test/Toxicity Test:

Using new drugs under development and environmental pollution-suspected chemicals as analytes, these tests can be carried out in a similar manner to the above (A) and (B).

(D) Test of Influence on Reproduction (In Vivo):

Using new drugs under development and environmental pollution-suspected chemicals as analytes, these tests can be carried out in a similar manner to the above (A) and (B).

(E) Test of Influence on Reproduction (In Vivo):

An expression vector to which an MSG gene (polynucleotide such as cDNA) is inserted and linked is constructed and then transferred into a host to prepare a transformant. The transformant is cultured in the presence of a new drug under development or an environmental pollution-suspected chemical. The present test can be carried out by judging whether the amount of its expression product or its function is normal or not. For example, Calmegin gene is expressed and the functional abnormality of the resulting Calmegin as shaperon is detected. Alternatively, by using such an expression vector, it is possible to detect or search substances which inhibit or accelerate its expressing ability and activity of an expressed product.

(F) Preparation of Experimental Animal:

For the purpose of carrying out analysis of in vivo functions of the MSGs and homologous genes thereof, animals wherein these genes are knocked out can be prepared. Moreover, for the purpose of analyses of regulator gene loci of these genes and activity thereof and also functions of gene products in individuals, transgenic animals can be prepared. Such experimental animals also enable development of medicaments and medical technologies for gene therapy and prevention of male infertility as well as preclinical test in development of contraceptives.

(G) Test with MSG-Transduced Transformant:

As in the above (F), an expression vector of an analyte gene DNA is constructed and its transformant is prepared. Then, abnormality of functions of its expression products is detected and also mutation of the analyte DNA and amino acid replacement induced by the mutation are analyzed. Contrastive analysis of both results thus obtained can creates meanings of correlation between function of an expressed product and the mutation.

(H) Amplified DNA by PCR:

By PCR using the primers of the invention, DNAs of animals or cultured cells under various experimental conditions can be amplified using these DNAs as templates. The basic procedure of PCR is described in, for example, the above literature (Current Protocol in Molecular Biology 1:15.0.1-15.3.8). Moreover, the experimental group DNAs amplified by PCR and their fragments or restriction enzyme fragments can be used for analyses of SSCP (single strand conformation polymorphism), RFLP (restriction fragment length polymorphism), EST, STS, GSS, SNP, and the like and for SAGE (serial analysis of gene expression). For example, they can be employed as analytes for polyacrylamide electrophoresis, as probes for DNA microarrays or DNA chips, and as probes for hybridization after labeling.

The following will describe human male infertility gene mutations of the invention.

The Scot-t mutant polynucleotide of the invention is a polynucleotide having any one or more mutations selected from the following:

-   -   “t” at 129th position is replaced by “c”;     -   “t” at 870th position is replaced by “g”;     -   “c” at 1071st position is replaced by “t”; and     -   “t” at 1667th position is replaced by “c”,         in the DNA sequence of SEQ ID NO:168 or a complementary sequence         thereof.

The Scot-t mutant polynucleotide can be isolated, for example, by screening a cDNA library prepared from whole mRNAs of a male infertile person using a Scot-t mutant oligonucleotide to be mentioned below as a probe. Also, the polynucleotide can be isolated by RT-PCR with the total mRNAs of a male infertile person as a template using the primer set of the invention to be mentioned below. Alternatively, it can be also obtained by transducing the above base replacement into wild-type Scot-t cDNA using a commercially available mutation kit or the like. The thus obtained cDNA can be amplified, for example, by conventional gene amplification methods such as PCR (polymerase Chain Reaction) method, NASBN (Nucleic acid sequence based amplification) method, TMA (Transcription-mediated amplification) method, and SDA (Standard Displacement Amplification) method.

The Scot-t mutant polynucleotide of the invention can be employed in the method for diagnosing male infertility according to the invention. Moreover, it is also used as a material for preparing the Scot-t mutant polypeptide of the invention to be mentioned below in a gene engineering manner.

The Scot-t mutant oligonucleotide of the invention is an oligonucleotide which is part of the above Scot-t mutant polynucleotide and which is composed of a continuous DNA sequence of 10 to 99 containing each mutation site, or a complementary sequence thereof.

The Scot-t mutant oligonucleotide can be prepared chemically by a known method. Moreover, it can be also prepared by cleavage of the Scot-t mutant polynucleotide with an appropriate restriction enzyme.

The Scot-t mutant oligonucleotide can be also employed in the method for diagnosing male infertility according to the invention. Alternatively, it is also used as a material for preparing the Scot-t mutant oligopeptide of the invention in a gene engineering manner.

The Scot-t mutant genomic polynucleotide of the invention is a polynucleotide (genomic DNA) derived from human chromosomal DNAs, which hybridizes the Scot-t mutant polynucleotide or Scot-t mutant oligonucleotide or a complimentary sequence thereof under stringent conditions. The stringent conditions mentioned here are conditions which enable a selective and detectable specific binding between the polynucleotide or olygonucleotide and a genomic DNA derived from a chromosome. The stringent conditions are defined by salt concentration, organic solvent (e.g., formamide), temperature, and the other known conditions. Namely, stringency is increased by reducing the salt concentration, increasing organic solvent concentration, or elevating hybridization temperature. For example, a stringent salt concentration is usually about 750 mM or less of NaCl and about 75 mM or less of trisodium citrate, more preferably about 500 mM or less of NaCl and about 50 mM or less of trisodium citrate, most preferably about 250 mM or less of NaCl and about 25 mM or less of trisodium citrate. A stringent organic solvent concentration is about 35% or more, most preferably about 50% or more of formamide. A stringent temperature condition is about 30° C. or higher, more preferably about 37° C. or higher, most preferably about 42° C. or higher. The other conditions include hybridization period of time, concentration of a washing agent (e.g., SDS), presence or absence of carrier DNA, and the like. By combining these conditions, various classes of stringency can be set. As one preferable embodiment, hybridization is carried out at 30° C. under conditions of 750 mM of NaCl, 75 mM of trisodium citrate, and 1% of SDS. As a more preferable embodiment, hybridization is carried out at 37° C. under conditions of 500 mM of NaCl, 50 mM of trisodium citrate, 1% of SDS, 35% of formamide, 100 μg/ml of denaturated salmon sperm DNA. As the most preferable embodiment, hybridization is carried out at 42° C. under conditions of 250 mM of NaCl, 25 mM of trisodium citrate, 1% of SDS, 50% of formamide, 200 μg/ml of denaturated salmon sperm DNA. In addition, conditions for washing after hybridization also affect stringency. The conditions for washing are also defined by salt concentration and temperature, and stringency at washing is increased by decrease of salt concentration and elevation of temperature. For example, stringent salt conditions for washing are preferably about 30 mM or less of NaCl and about 3 mM or less of trisodium citrate, most preferably about 15 mM or less of NaCl and about 1.5 mM or less of trisodium citrate. A stringent temperature condition is about 25° C. or higher, more preferably about 42° C. or higher, most preferably about 68° C. or higher. As one preferable embodiment, washing is carried out at 25° C. under conditions of 30 mM of NaCl, 3 mM of trisodium citrate, and 0.1% of SDS. As a more preferable embodiment, washing is carried out at 42° C. under conditions of 15 mM of NaCl, 1.5 mM of trisodium citrate, and 0.1% of SDS. As the most preferable embodiment, washing is carried out at 68° C. under conditions of 15 mM of NaCl, 1.5 mM of trisodium citrate, and 0.1% of SDS.

The Scot-t mutant genomic polynucleotide can be isolated by screening a genome library, which is prepared from chromosomal DNAs of a male infertile person, by stringent hybridization as above using Scot-t mutant oligonucleotide as a probe and washing treatment.

The Scot-t mutant genomic polynucleotide may be a detection target in the method for diagnosis according to the invention.

The Scot-t primer set of the invention is a primer set for PCR amplification of the Scot-t mutant polynucleotide, a double-stranded polynucleotide composed of the Scot-t mutant genomic polynucleotide and its complementary sequence, or mRNA transcribed from the Scot-t mutant genomic polynucleotide. In these primer sets, one oligonucleotide primer is composed of a continuous DNA sequence of 15 to 45 nt, preferably 15 to 30 nt containing at least one nucleotide mutation site of SEQ ID NO:168 (Scot-t cDND) or a complementary sequence thereof. Another primer may be any continuous DNA sequence at 5′-side or 3′-side of each mutation site of SEQ ID NO:168 or a complementary sequence thereof.

These primer sets can be prepared by a known process for DNA synthesis based on SEQ ID NO:168 containing each mutation site. Moreover, at the terminal of the primer, a linker sequence or the like may be added. Furthermore, for designing the sequence, commercially available software, for example, Oligo™ [manufactured by National Bioscience Inc., (USA)], GENETYX [manufactured by Software Development K.K. (Japan)], or the like may be employed.

The Scot-t primer sets of the invention can be employed in the method for diagnosing male infertility according to the invention.

In the protamine-2 mutant polynucleotide of the invention, c at 248th position in SEQ ID NO:173 (protamine-2 cDNA) is replaced by t.

The protamine-2 mutant oligonucleotide, mutant genomic polynucleotide, protamine-2 primer sets of the invention can be obtained and used in the same manner as in the case of the above invention relating to Scot-t.

The Scot-t mutant polypeptide of the invention is a polypeptide which is an expression product of the Scot-t mutant polynucleotide or mutant genomic polynucleotide of the above invention and which has one or more mutations selected from the following group:

-   -   Leu at 38th position is replaced by Pro;     -   Leu at 285th position is replaced by Arg; and     -   Thr at 352nd position is replaced by Met,         in the amino acid sequence of SEQ ID NO:169.

Namely, in these Scot-t mutant polypeptide, amino acids in the normal (wild-type) polypeptide (SEQ ID NO:169) are mutated as above by missense mutation in the Scot-t mutant polynucleotide of the above invention.

The protamine-2 mutant polypeptide is a short-chain polypeptide which is an expression product of the protamine-2 mutant polynucleotide of the above invention and which is composed of an amino acid sequence of 1st to 49th positions in the amino acid sequence of SEQ ID NO:174. Namely, the polypeptide is a short-chain polypeptide which is formed by mutation of 50th glutamic acid codon into a stop codon by one base replacement (c by t) at 248th position of the protamine-2 mutant polynucleotide and as a result of no expression of the following protein-encoded region from the position.

These mutant polypeptides are obtained by a process for isolation from a biological sample of a male infertile person according to a known method, a process for preparing peptides by chemical synthesis based on an amino acid sequence of SEQ ID NO:169 or 174 containing each mutant amino acid residue, or a process for production by a recombinant DNA technology using mutant polynucleotide (mutant cDNA) of the above invention. These mutant polypeptides may be employed as test target in the method for diagnosing male infertility according to the invention.

The mutant oligopeptides of the invention are oligopeptides which are parts of the respective mutant polypeptides of the above invention and which have an continuous amino acid sequence of 5 to 30 containing each amino acid mutation site. These mutant oligopeptides can be prepared by a process of chemical synthesis based on a predetermined amino acid sequence or a process of digesting the above mutant polypeptides with an appropriate protease. These oligopeptides can be employed, for example, as antigens for antibody preparation according to the invention.

The anti-mutant Scot-t antibody, anti-mutant protamine-2 antibody, and anti-protamine-2 antibody of the invention are polyclonal antibodies or monoclonal antibodies prepared using the oligopeptides of the above invention as antigens and include all of whole molecules capable of binding to epitopes of the mutant polypeptides of the invention, and Fab, F(ab′)₂, Fv fragments, and the like. Such antibodies can be prepared in a similar manner to the case of antibodies described for the MSGs invention. Moreover, these antibodies can specifically recognize the above mutant polypeptides and thus employed in the methods for diagnosis according to the invention.

The method for diagnosis according to the invention is a method for diagnosing whether a subject person suffers from male infertility or not. Namely, chromosomal DNAs are isolated from a biological sample of the subject person and, in the case that the mutant genomic polynucleotide of the above invention is present in the DNAs, the subject person is judged to be a high-risk person of male infertility. The subject person may be an infertile male person or a boy having an infertile male person in relations on his mother's side, but is not limited thereto. The mutant polynucleotide can be also detected by a method of directly sequencing it but the following methods are preferable.

First, it is detected whether chromosomal DNAs isolated from the subject person or mRNAs thereof hybridize the Scot-t mutant polynucleotide and/or protamine-2 mutant polynucleotide or respective mutant oligonucleotides under stringent conditions. In the case that the subject person possesses a gene mutation associated with male infertility, the chromosomal DNAs or the mRNAs and mutant polynucleotides or mutant oligonucleotides hybridize even under stringent conditions. The hybridization can be detected by a known method. For example, the detection can be carried out conveniently and at a high accuracy using the DNA probe or DNA chip of the invention. As a hybridization method using a labeled DNA probe, specifically known methods, for example, Allele-specific Oligonucleotide Probe method, Oligonucleotide Ligation Assay method, Invader method, or the like can be adopted. Moreover, the DNA chip may be a chip wherein the mutant polynucleotides and/or mutant oligonucleotides are directly synthesized on a substrate or a chip wherein the oligonucleotides are spotted on a substrate coated with a material to which nucleotides may bind. Nucleotide mutation in a test sample DNA can be identified using presence of hybridization of the labeled test sample DNA and the oligonucleotides on the substrate as an indicator.

In the second preferable method, presence of a PCR product is detected in the case that PCR is carried out with a primer set of the above invention using chromosomal DNA or mRNA isolated from the subject person as a template. When the subject person possesses gene mutation associated with male infertility, a PCR product of the polynucleotide defined by the primer set is obtained. PCR or RT-PCR can be carried out by a known method. Nucleotide mutation may be detected by, other than a method of direct sequencing of a PCR product, PCR-SSCP method, PCR-CFLP method, PCR-PHFA method, or the like. Moreover, a known method such as Rolling Circle Amplification method or Primer Oligo Base Extension method can be also employed.

In the application of another method for diagnosing male infertility of the invention, in the case that the Scot-t mutant polypeptide and/or protamine-2 mutant polypeptide of the above invention is present in a biological sample isolated from a subject person, the subject person is judged to be a high-risk person of male infertility. Although the polypeptides can be detected by various known method, one preferable method is a method of detecting the Scot-t mutant polypeptide using an anti-mutant Scot-t antibody. Moreover, it is a method of combined use of an anti-mutant protamine-2 antibody and an anti-protamine-2 antibody (an antibody prepared using an oligopeptide composed of an amino acid sequence of 50th to 91st positions in SEQ ID NO:7 or of 1st to 11th positions in SEQ ID NO:8). Namely, in the case of short-chain protamine-2 mutant polypeptide, the anti-mutant protamine-2 antibody reacts but the anti-protamine-2 antibody prepared using long-chain protamine-2 polypeptide does not react.

In the case of the method for diagnosis using the above antibodies, a convenient and highly accurate detection is possible especially by using a labeled antibody in this invention. For the labeling, an enzyme, radioactive isotope, or fluorescent dyestuff can be employed. The enzyme is not particularly limited as far as it satisfies requirements that it has a large turnover number, it is stable even when combined with an antibody, it specifically colors a substrate, and the like. Use can be made of enzymes usable for usual EIA, for example, peroxydase, β-galactosidase, alkaline phosphatase, glucose oxidase, acetylcholine esterase, glucose-6-phosphorylation dehydrogenase, malate dehydrogenase, and the like. Moreover, an enzyme-inhibiting substance, coenzyme, and the like can be also employed. The combination of the enzymes with an antibody can be effected by a known method using a crosslinking agent such as maleimide compound. As the substrate, a known substance can be employed in accordance with the kind of enzyme to be used. For example, 3,3′,5,5′-tetramethylbenzidine can be used in the case that a peroxidase is used as the enzyme, and p-nitrophenol can be used in the case that alkaline phosphatase is used as the enzyme. As the radioisotope, those used in usual RIA, such as ¹²⁵I and ³H can be employed. As the fluorescent dyestuff, those used in usual fluorescence antibody methods, such as fluorescence isothiocyanate (FITC) and tetramethylrhodamine isothiocyanate (TRITC), can be used. In the case of using an enzyme, enzyme activity is determined by adding a substrate which is decomposed by the action of the enzyme to develop color and then optically measuring the decomposed amount of the substrate, the activity is converted into an amount of bound antibody, and an amount of the antibody is calculated based on the comparison with standard values. In the case of using a radioactive isotope, amount of radiation emitted by the radioactive isotope is measured by a scintillation counter or the like. Moreover, in the case of using a fluorescent dyestuff, an amount of fluorescence may be measured by a measuring equipment combined with a fluorescent microscope. Furthermore, a sandwich method using a primary antibody and a labeled secondary antibody (“ELISA method” in the case of using an enzyme as a label) can be also preferably employed.

EXAMPLES

The following will specifically describe embodiments and compositions and advantages of the invention with reference to Examples and Use Examples but the invention of this application is not limited these examples.

Example 1 Preparation of Mouse Total RNA

Each testis was excised from the following two groups of mice (C57BL/6), 19 mice of 17 days old and 5 mice of 35 days old and collected into one capsule per group. Thereto was added 50 ml of 5.5M GTC solution (pH 7.5; 5.5M guanidine thiocyanate, 25 mM sodium citrate 2H₂O, 0.5% (W/V) sodium lauryl sarconate, and 0.2M 2-mercaptethanol), and then the mixture was passed through a syringe with a 18G needle to break the cells. Then, the mixture was subjected to low-speed centrifugation and the supernatant was collected to remove precipitated cell fragments. Fifty milliliters of the collected supernatant was transferred into two tubes, in which 14 ml of CsTFA (cesium trifluoroacetate) solution was placed, in an amount of 25 ml each, followed by ultra-centrifugation (25,000 rpm, 15° C., 24 hours). RNA precipitated by the ultra-centrifugation was dissolved in 600 μl of 4.4M GTC solution/tube and then precipitated with ethanol. The precipitated RNA was dissolved in TE [10 mM Tris-HCl (pH 7.5), 1 mM EDTA], and then recovered by re-precipitation with ethanol to obtain total RNA of each of both groups of 17 day-old and 35 day-old mice.

Example 2

Preparation of Mouse mRNA[Poly(A)+]

Each of the total RNA in two tubes (two groups) in an ethanol-precipitated state obtained in Example 1 was rinsed with 70% (V/V) ethanol, and then 500 μl of the above TE/tube was added to dissolve the RNA, followed by heating at 65° C. for 5 minutes and rapid cooling on ice. Then, 500 μl of 1M NaCl/tube was added thereto and the resulting mixture was loaded on an oligo(dT)cellulose column [Type 3; manufactured by Collaborative Research] equilibrated with TE/NaCl (TE: 1M NaCl=1:1) beforehand. Each column was washed with 8 ml of the above TE/NaCl and then each was eluted with 0.5 ml of TE to achieve fractionation. This fractionation was repeated 5 times in total and a portion of each fraction was taken out and mixed with EtBr (ethidium bromide). Thereafter, the second fraction from which fluorescent radiation was observed under UV irradiation was adopted as an mRNA fraction. On the second fraction, the above operations from heating at 65° C. for 5 minutes to column fractionation was repeated again. After precipitation of the resulting fraction with ethanol, the precipitate was rinsed with 70% (V/V) ethanol and dissolved in 10 μl of TE. A portion thereof was taken out and quantitative determination was conducted on an absorptiometer.

Example 3 Preparation of cDNA Library of 35 Day-Old Mouse Testis

It was prepared according to the procedure described in the following (1) to (6).

(1) Synthesis of First Strand (Preparation of Single-Stranded, ss-cDNA):

Seven micrograms of mRNA of 35 day-old mouse obtained in Example 2 was weighed out and distilled water was added thereto to make the total amount 7.5 μl, followed by heating at 65° C. for 5 minutes and then cooling with ice. Thereafter, the following reagents were added and mixed: 2.5 μl of 10×1st strand buffer [500 mM Tris-HCl (pH 8.3), 750 mM KCl, 30 mM MgCl₂], 2.5 μl of 0.1M DTT (dithiothreitol), 1.5 μl of 1st strand methyl nucleotide mixture (10 mM dATP, dGTP and dTTP; and 5 mM 5-methyl-dCTP), 1 μl (1.6 μg) of linker primer [(GA) 10ACGCGTCGACTCGAGCGGCCGCGGACCG(T) 18], 0.5M1 of RNase inhibitor, and 7.5 μl of H₂O. The whole was left on standing at room temperature for 10 minutes to effect annealing and then 2 μl of a reverse scriptase [manufactured by Seikagaku Corporation (Japan)] was added thereto, followed by reaction at 37° C. for 40 minutes. Then, 2 μl of Super Script [manufactured by BRL (USA)] was added and mixed and then the whole was allowed to react at 50° C. for 40 minutes to obtain a single-stranded first strand (ss-cDNA).

(2) Synthesis of Second Strand (Preparation of Double-Stranded, ds-cDNA):

To the first strand solution obtained in the above (1) was added the following reagents on ice and the whole was mixed: 20 μl of 10×2nd strand buffer [188 mM Tris-HCl (pH 8.3), 906 mM KCl, 46 mM MgCl₂], 7.5 μl of 0.1M DTT, 3 μl of 2nd strand nucleotide mixture (10 mM DATP, dGTP and dTTP; and 25 mM 5-methyl-dCTP), and 135 μl of H₂O. The whole was cooled with ice for 5 minutes and then 1.5 μl (2 units) of RNase H and 6 μl (50 units) of Escherichia coli DNA polymerase I were added and mixed, followed by reaction at 16° C. for 180 minutes. After completion of the reaction, cDNA was extracted with 200 μl of phenol/chloroform (water-saturated phenol:chloroform=1:1 mixture) and chloroform, successively, and then was dissolved in 30 μl of 1/10 TE to obtain a double-stranded second strand (ds-cDNA).

(3) Blunt End Formation (Preparation of Blunt End ds-cDNA):

To 30 μl of the ds-cDNA solution of the above (2) was added the following reagents, and the whole was mixed: 10×T4 DNA polymerase buffer [500 mM Tris-HCl (pH 8.3), 100 mM MgCl₂, 500 mM NaCl, 100 mM DTT], 2.5 mM dNTP mixture, 1 μl (10 units) of T4 DNA polymerase, and 54 μl of H₂O; the total amount was 100 μl. Then, after a reaction at 37° C. for 30 minutes (keeping the period strictly), cDNA was extracted with 100 μl of the above phenol/chloroform and chloroform, successively, and then was dissolved in 20 μl of 1/10 TE to obtain a blunt ended ds-cDNA.

(4) Linkage of Adaptor:

To 4 μl of the blunt ended ds-cDNA solution of the above (3) was added the following reagents, and the whole was mixed and then cooled with ice for 5 minutes: 2 μl of 10× ligase buffer [500 mM Tris-HCl (pH 8.3), 70 mM MgCl₂, 10 mM DTT], 2 μl of 10 mM ATP, 1 μl (0.35 μg) of an adaptor, and 9.5 μl of H₂O; the total amount was 18.5 μl. The above adaptor is a 1:1 (W/W) mixture of BamH I(Bgl II)-Sma I[d(GATCCCCGGG)] [manufactured by Takara Shuzo Co., Ltd.] and pSma I linker[d(pCCCGGG)] [manufactured by Takara Shuzo Co., Ltd.] and was prepared by dissolving them in a buffer [10 mM Tris-HCl (pH 7.5), 1 mM EDTA, 10 mM MgCl₂] to have a concentration of 0.35 μg/μl. Then, 1.5 μl (4 units) of T4 ligase was added and mixed. After a reaction at 8° C. overnight, the whole was heated at 70° C. for 30 minutes and then centrifuged at 15,000 rpm at 4° C. for 5 seconds, the supernatant being obtained as an adaptor-linked ds-cDNA.

(5) Preparation of Restriction Enzyme Fragments of ds-cDNA and Fractionation by Spin Column:

To the adaptor-linked ds-cDNA solution of the above (4) was added 27 μl of Not I buffer [278 mM NaCl, 8 mM MgCl₂, 1.8 mM DTT, 0.01% (W/V) BSA (bovine serum albumin), 0.018% (W/V) Triton X-100] and 3 μl of Not I (10 units), respectively and the whole was mixed, followed by a reaction at 37° C. for 150 minutes. After completion of the reaction, 5 μl of 10×STE [1M NaCl, 100 mM Tris-HCl (pH 8.3), 10 mM EDTA (pH 8.0)] and 10 μg of tRNA were added and mixed. The resulting mixture was placed in Chroma Spin columns [manufactured by Clontech (USA)] in an amount of 10 μl/column and centrifuged at 4° C. at 1,800 rpm for 5 minutes and then a fraction of restriction enzyme fragment at a bottom of the centrifugal tubes was collected. Then, the fragment was extracted with equivalent amount of phenol/chloroform and chloroform, successively, and then 10 μg of tRNA was replenished and the total amount is made 250 μl with adding water. Furthermore, precipitation with ethanol was carried out and the precipitate was rinsed with 70% (V/V) ethanol and then slightly dried to obtain a restriction enzyme (Not I/Bgl II) fragment of the adaptor linked ds-αDNA.

(6) Insertion and Linkage of ds-Restriction Enzyme into a Vector:

To the slightly dried product of the ds-DNA restriction enzyme (Not I/Bgl II) fragment of the above (5) was added the following reagents, and the whole was mixed and then cooled with ice for 5 minutes: 3 μl of the above 10× ligase buffer, 3 μl of 10 mM ATP, 1 μl (1 μg) of a plasmid vector pAP3neo (restriction enzyme Not I/Bgl II cleavage), and 22 μl of H₂O. Then, 1 μl (4 units) of T4 DNA ligase was added and mixed. After a reaction at 12° C. overnight, the whole was heated at 70° C. for 30 minutes. After extraction with phenol/chloroform and chloroform, successively, the product was dissolved in 20 μl of TE to obtain a solution of a plasmid vector to which the ds-cDNA was inserted. Then, using the whole amount of the solution, ds-cDNA-inserted plasmid vector was transferred into a competent cell, Escherichia coli by electroporation to effect transformation. The resulting transformant was provided as a cDNA library of 35 day-old mouse testis, for the preparation of a subtracted library in Experiment 4 to be mentioned below.

Example 4 Preparation of Subtracted Library of Mouse

According to the procedures (1) to (5) described below, a subtracted library was prepared by subtracting expression genes (mRNA:B) in 17 day-old mouse testis from the cDNA library (A) of 35 day-old mouse testis obtained in Experimental Example 3 by hybridization. In order to remove also genes over expressed prior to the appearance of haploid by the subtraction, the reactant ratio of A/B=1/40 was adopted in the hybridization.

(1) Conversion of cDNA Library (A) of 35 Day-Old Mouse Testis into Single-Stranded Ones

The transformant (Escherichia coli) of the cDNA library obtained in (6) of Experiment 3 was cultured at 37° C. for 1 hour in 4 ml of SOC [2% (W/V) Bacto-tryptone, 0.5% (W/V) yeast extract, 10 mM NaCl, 2.5 mM KCl, and 20 mM glucose] medium. Thereafter, it was transferred into 100 ml of LB/Amp [1% (W/V) Bacto-tryptone, 0.5% (W/V) yeast extract, 0.5% (W/V) NaCl, 50 μg/μl ampicillin] medium and further cultured at 37° C. for 4.5 hours to amplify the cDNA. Among 100 ml of the resulting culture solution, 50 ml thereof was transferred into another vessel and 1 ml of a helper phage (R408; 2×10¹² pfu (plaque-formation unit)/ml) was added thereto, followed by culturing at 37° C. for 10 hours. The remaining 50 ml of the culture solution was frozen and stored under addition and mixing of DMSO at a final concentration of 7% (V/V) after the culture at 37° C. without further treatment. After completion of the culture, fungi were removed by centrifugation and collected supernatant was filtrated through a filter having a pore size of 0.2 μm to remove Escherichia coli debris completely. Then, to 50 ml of the culture filtrate was added the following reagents, and the whole was mixed: 5 ml of Dnase I solution [0.1M Tris-HCl (pH 7.5) and 0.1M MgCl₂] and 5 μl of Dnac I. The whole was reacted at 37° C. for 30 minutes and then 20% (W/V) PEG (polyethylene glycol; solvent was 2.5M NaCl) was added to a quarter of the whole and mixed, followed by further reaction at room temperature for 20 minutes. Then, the phage was collected by ultracentrifugation at 4° C. at 10,000 rpm for 10 minutes and, after supernatant was discarded and PEG was completely removed, the phage was suspended in 400 μl of TE. Thereto were added 25 μl of Proteinase K solution (solution composed of 2 mg of Proteinase K, 800 μl of TE, and 200 μl of glycerol) and 4 μl of 10% (W/V) SDS (sodium dodecyl sulfate), and the whole was mixed, followed by a reaction at 42° C. for 1 hour. After completion of the reaction, extraction was carried out with phenol, phenol/chloroform, and chloroform, successively, and precipitation with ethanol was carried out. The precipitate was rinsed with 70% (V/V) ethanol and then dissolved in 100 μl of TE, a portion of which was quantitatively determined using a ultraviolet spectrometer.

(2) Biotinylation of 17 Day-Old Mouse Testis mRNA

Distilled water was added to a tube containing 40 μg of 17 day-old mouse testis mRNA obtained in Experimental Example 2, and the total amount was made 20 μl. Thereto was added 30 μl of biotin (photoprobe biotin 1 μg/μl aqueous solution)[manufactured by Vector Laboratories (USA)], followed by mixing. After thorough pipetting, the tube was placed on ice with the cap off and labeling was carried out by irradiating the tube with a mercury lamp (BHRF100/110 v/60 W) from 10 cm above the tube for 20 minutes. After completion of the labeling, 50 μl of 0.1M TE (pH 9.5) was added thereto and, after thorough pipetting, 100 μl of water-saturated butanol was added and excess of biotin was removed. Furthermore, 100 μl of chloroform was added to remove butanol, and then precipitation with ethanol and rinsing with 70% (V/V) ethanol were successively carried out, followed by dissolution into 20 μl of distilled water. The above labeling operation was repeated again and finally the product was dissolved in 10 μl of distilled water to form a biotinylated mRNA aqueous solution.

(3) Hybridization

The following reagents were added to a PCR tube and mixed together carefully so as not to contain bubbles: 1.5 μl (0.5 μg) of ss-cDNA prepared in the above (1), 5 μl (20 μg) of the biotinylated mRNA obtained in (2), 12.5 μl of 2×HB [80% (W/V) formamido, 100 mM HEPES, 2 mM EDTA, and 0.2% (W/V) SDS; prepared just before use], 2.5 μl of 2M NaCl, and 1 μl of Poly A (1 μg/μl aqueous solution) [manufactured by Pharmacia (Sweden)], 2.5 μl of distilled water. It was reacted at 65° C. for 10 minutes and further at 42° C. for 43 hours to effect hybridization.

(4) Recovery of ss-cDNA by Reaction with Avidin

Into another tube was transferred 25 μl of the reaction solution obtained in the above (3), and then 400 μl of SB [50 mM HEPES (pH 7.5), 2 mM EDTA, and 500 mM NaCl], and 10 μg of streptoavidin [manufactured by Gibco BRL (USA)] were added thereto and the whole was mixed. After a reaction at room temperature for 5 minutes, ss-cDNA not hybridized was extracted with 400 μl of phenol/chloroform (1:1 equivalent mixture). The above operations from the avidin-addition to extraction with phenol/chloroform was repeated again. Thereafter, further extraction with chloroform was carried out and purified ss-cDNA was recovered by millipore filter. Then, it was dissolved in 30 μl of 1/10 TE and then 15 μl thereof was transferred into another tube (the remainder was stored at −20° C.) and concentrated (not completely dried) by vacuum drying for 10 minutes.

Furthermore, the above operations from hybridization to vacuum drying were repeated twice. The composition at the second and third hybridization was as follows: ss-cDNA concentrated by the above vacuum drying, 5 μl (10 μg) of the biotinylated mRNA, 12.5 μl of 2×HB, 2.5 μl of 2M NaCl, and 1 μl of Poly A, total amount of which was made 25 μl by adding distilled water. Moreover, of 30 μl of ss-cDNA obtained by second hybridization, 15 μl was used for third hybridization and the remainder was stored at −20° C.

(5) Conversion of ss-cDNA into Double-Stranded One

Fifteen microliters of PNK reaction mixture was added to and mixed with 15 μl of the ss-cDNA solution obtained in the above (4), followed by a reaction at 65° C. for 10 minutes. The PNK reaction mixture was prepared by reacting the following composition at 37° C. for 30 minutes: 1 μl of primer oligonucleotide for double strand formation, 3 μl of 10× ligation buffer [500 mM Tris-HCl (pH 7.5), 70 mM MgCl₂, and 10 mM DTT], 3 μl of 10 mM rATP, 2 μl of PNK (T4 polynucleotide kinase; 10 units/μl) [manufactured by Toyobo Co., Ltd. (Japan)], and 21 μl of distilled water were added and the total amount was made 30 μl. After completion of the reaction, the mixture was cooled to room temperature and then the following reagents were added to 30 μl of the reaction solution and the whole was mixed, followed by further reaction at 65° C. for 1 hour: 5 μl of 10×BcaBEST Buffer [manufactured by K.K. Takara (Japan)], 10 μl of 1 mM dNTP, 0.5 μl of single strand DNA binding protein (2.1 μg/μl) [manufactured by USB (USA)], 2 μl of BcaBEST DNA polymeraze [manufactured by K.K. Takara (Japan)], and 3 μl of distilled water were added and the total amount was made 50 μl. After completion of the reaction, extraction with 100 μl of phenol/chloroform and chloroform was successively carried out and purified ds-cDNA was recovered by filtration through millipore filter. Then, it was dissolved in 20 μl of TE and a portion thereof was transferred into Escherichia coli (XL-1 Bleu) by electroporation to effect transformation. The thus obtained transformant was used for MSG cloning as a subtracted library, i.e., MSG-candidate cDNA library.

Example 5 Cloning of MSG

Northern blotting was carried out between ss-cDNA prepared, in a similar manner to the description in (1) of Experimental Example 4, from the culture solution of transformant containing the MSG-candidate cDNA library of the subtracted library prepared in Experimental Example 4 and total RNA of both testis of 17 day-old and 35 day-old mice obtained in Experimental Example 1, and cDNA whose signal was detected only in 35 day-old mouse was screened and collected. As a result, 79 MSG clones were obtained in total. Moreover, when clones obtained by cloning with monoclonal antibody and polyclonal antibody were combined, 89 MSG clones were obtained in total.

Example 6 Determination of Base Sequence of MSG Clone DNA

After MSG clones/vectors were amplified by culturing respective transformant of MSG library obtained in Example 5, respective vectors (plasmids) were extracted and purified by alkali method. Then, based on dideoxy method (Sanger method), sequences of respective cDNAs of 89 MSG clones in total obtained in Example 1 were determined. The results are shown in SEQ ID NO:1 to 89.

Example 7 Investigation of ED Action Against MSG

As one model of ED discharged into the environment, change in expression of MSG gene by administration of DES having estrogen action was investigated using mouse.

To a 8 week-old C57BL/6 male mouse, DES was intraperitoneally injected twice every two days. After two days, both testes were taken out and one was subjected to tissue observation while RNA was extracted from another one to compare a gene expression level.

-   Material: mouse: 8 week-old C57BL/6 male mice -   Administration DES Concentration and Number of Mice:     -   1: no treatment (two mice)     -   2: 0 μg DES in corn oil (two mice)     -   3: 1 μg DES in corn oil (two mice)     -   4: 10 μg DES in corn oil (two mice)     -   5: 50 μg DES in corn oil (three mice)         Experimental Schedule:

On the first day, no treatment or each amount of DES dissolved in 20 μl of corn oil was intraperitoneally injected. On the third day, the same treatment was conducted as in the first day. On the fourth day, testes were taken out. One of them was fixed with Buan and embedded in paraffin, and then subjected to HE stain, followed by tissue observation. Another one subjected to RNA extraction with Trizol and the gene expression level was compared by Northern hybridization.

-   Analyzed gene: OAZt (Ornithin decarboxylase antizyme-t): SEQ ID     NO:50     Results:

It was impossible to detect morphologically evident change. However, as a result of Northern hybridization on a spermatid-specifically expressing gene OAZt, individual difference was very large but, as a whole, the treated group showed a low level.

OAZ-t is a gene exhibiting a haploid spermatid-specific expression. It was suggested that initiation of the expression was suppressed by DES. In spit of such a low concentration and a short-term DES treatment that no morphological anomaly was observed, difference was detected at a gene expression level. This fact indicates that the method of the invention is sufficiently applicable as a highly sensitive detecting system at an individual level of influence of estrogen on male germ cells.

Example 8 Functional Analysis of Mouse Haspin

Haspin (SEQ ID NO:81) is a protein kinase which is spermatid-specifically expressed. It has various functional domain (nucleus-transferring signal, leucine zipper, transcription factor-like structure) including a kinase domain and is involved in various spermatid functions, so that it is considered to play important roles in spermatogenesis. Furthermore, when haspin gene is expressed in cultured cells, it is also known that the protein transfers into nuclei and growth of the cells was stopped at G1 stage (J. Biol. Chem. 274, 17049-17057, 1999).

The following are revealed about the haspin.

Analysis of Hapsin-Knockout Mouse:

Using thymidine kinase (TK) gene and neomycin (neo) resistance for selection, haspin gene of an ES cell was broken and a haspin gene-defective (haspin KO) mouse was prepared by preparing mouse embryo from the ES cell. The individual of the KO mouse normally developed and grew but male mouse exhibited infertility and fertility was observed in female mouse. Moreover, no apparent disorder was observed in spermatogenesis and morphologically not abnormal sperm was produced but it was confirmed that the mouse exhibited male infertility owing to dysfunction.

Analysis of Expression Regulatory Region of Hapsin Gene:

A transgenic (TG) mouse was prepared using a reporter gene wherein GFP gene was linked to 192 bases at upstream of haspin gene. As a result of the analysis of the TG mouse, GFP was expressed in a haploid spermatid specific manner, so that it was confirmed that the region comprising the 192 bases was a promoter which regulates the specific expression of haspin gene.

Analysis of Interactive Protein with Hapsin Molecule:

From the experimental results of yeast 2 hybrid system, it was revealed that there exist at least 8 kinds of intratesticular proteins interacting with haspin molecule. These proteins play important roles in spermatogenesis through interaction with human (Mol. Hum. Reprod. 7, 211-218, 2001) or mouse haspin.

Based on these results, the following may be applicable. Namely, since it was confirmed that genetic deficit of haspin causes male infertility,

-   1) it is possible to cause male infertility by dysfunction of haspin     itself or dysfunction of a protein interacting therewith; -   2) it is possible to cause infertility by inhibiting interaction     between haspin and the other molecule; and -   3) it is possible to cause infertility by inhibiting transfer of     haspin to nucleus.

Namely, the inventors have found out a protein directing the specific transfer to nucleus (importin alpha) among molecules interacting with haspin. Dysfunction of the importin alpha can inhibit the transfer of haspin to nucleus and cause functional deficit of haspin.

-   4) it is possible to cause infertility by the action of an inhibitor     against kinase activity of haspin.

Namely, since specific inhibitors against various kinases have hitherto been developed, it is highly probable to develop an inhibitor against a highly specific kinase such as haspin.

Moreover, the haspin promoter identified as above specifically expresses only in haploid spermatid, but by activating the promoter in somatic cells, it is also possible to regulate the growth of abnormally growing cells. The activation of the promoter can be achieved by introduction of a specific transcription factor effective thereon or a gene thereof. Alternatively, it can be achieved by a method of activating gene expression of its transcription factor.

Example 9 Detection of ED in Mouse

A 10 day-old mouse (male) was reared for 200 days with continuous administration of an ED-suspected analyte (Bisphenol A or the like) orally. Irrespective of observed anomaly on reproduction function, behavior, or appearance thereof, cellular RNA and chromosomal DNA were extracted from the testis of the reared mouse using an RNA extraction kit (e.g., TOLIzol: GIBCO BRL) and a DNA extraction kit (e.g., DNAzol BD Reagent: Oriental Yeast (Japan)). The RNA was investigated on change of expression level by Northern blotting and with regard to the DNA, amplification of spermatogenesis gene(s) was carried out using the PCR primer obtained in Example 5. Thereby, when the amplification was impossible, it was judged that the gene(s) possess a large mutation. When the amplification is possible, the amplified DNA fragments were directly sequenced or, after fragmentation with an endonuclease which recognizes and cleaves a specific DNA base sequence, the fragments were subjected to agarose gel or polyacrylamide gel electrophoresis and then analyses of SSCP, RFLP, EST, STS, GSS, and SNP were carried out to detect mutation. A DNA fragment in which mutation was detected was further subjected to determination of its base sequence and then judged on the following points by computer analysis: whether the mutation is polymorphism or not; whether the mutation causes modulation during the process of regulation, duplication, and transcription of the gene(s); and whether the mutation induces a large disorder on the function of translation product(s) (protein(s)). Based on these change in RNA and DNA, ED was detected.

Example 10 Analysis of Human Scot-t Gene and Protamine Gene

1. Methods

1-1. Subject Person and Extraction of Genomic DNA

For the analysis of Scot-t gene, a total of 255 cases of male infertility patients were classified into a plurality of subordinate groups in accordance with spermatology. 152 cases (60%) were nonobstructive azoospermia, 72 cases (28%) were severe oligospermia (from 0.1 to 3×10⁶ cell/ml), 27 cases (11%) were low sperm motility, and 4 cases (2%) were idiopathic infertility wherein number, morphology and motility of sperm were normal. As a control group, the subjects were 261 cases of reproducible male persons who were husbands of pregnant wives visited maternity hospitals.

For the analysis of protamine genes, a total of 258 cases of male infertility patients were classified into a plurality of subordinate groups in accordance with spermatology. 153 cases (59%) were nonobstructive azoospermia, 73 cases (28%) were severe oligospermia (number of sperm: less than 5×10⁶ cell/ml), 28 cases (11%) were asthenozoospermia where sperm motility was low, and 4 cases (2%) were idiopathic infertility wherein number, morphology and motility of sperm were normal. As a control group, the subjects were 270 cases of healthy persons as mentioned above.

Genomic DNA of each of the above infertile patients and healthy persons was extracted by a known method using a protease and phenol (Sambrook and Maniatis, in Molecular Cloning—A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York, 1989) and used.

1-2. Identification of Mutation in Human Scot-t Genomic DNA

Since human Scot-t contains a pseudo-gene having 19 bp deletion (18 nucleotides of 745th to 762nd and one nucleotide of 778th intervening 15 nucleotides) at the central part of a coding region (Tanaka H, et al., Mol Human Reprod 2001; 8: 16-23), two kinds of PCR primers containing the deleted region were prepared so that the pseudo-gene was not amplified. Namely, For the amplification of 5′ half, use were made of 25 oligonucleotide (tgctctgtgacgcgcggcccgaggc: SEQ ID NO:176) at upstream of presumed transcription initiation site and 26 oligonucleotide (cctccacgatctcttccacctccacc: SEQ ID NO:177) of from 770th to 745th, 24 oligonucleotide (cggtggaggtggaagagatcgtgg: SEQ ID NO:183), and 25 oligonucleotide (tccattcctcaccactgcacacctg: SEQ ID NO:178) at downstream of presumed transcription unit (cf. FIG. 1).

Determination of the total sequence of the h-Scot-t DNA except for 35 nucleotides located around the internal primer sequence (730-764) around the central part was able with using 2 kinds of PCR amplification fragments covering the left side and the right side of the n-Scot-t gene (FIG. 1).

1-3. Introduction of Various SNP Types of Genes into Recombinant h-Scot-t cDNA and Analysis of Succinyl CoA Tranferase Activity

On 72 hours after transfection of each cDNA using CaPO₄, HEK 293 cell was lysed. Each cell lysis solution (5 mg protein) was subjected to a chromatographic treatment using HPLC to separate into exogenous SCOT-t and endogenous SCOT-s, followed by analysis of enzyme activity. Standardization of succinyl CoA transferase activity was carried out using a relative amount of h-SCOT-t protein evaluated on a densitometer from Western blotting signals using anti-SCOT-t antibody.

SCOT enzyme activity was carried out by a method described in a literature (Marcondes, S, et al. (2001) Proc. Natl. Acad. Sci. USA. 98, 7146-7151) with slight modification. Namely, content of the analyte mixture were 50 mM Tris-HCl (pH 8.5), 0.2 mM succinyl CoA, 5 mM lithium acetoacetate, 5 mM MgCl₂, 5 mM iodoacetamide, and an h-SCOT-t fraction. Spectroscopic analysis of SCOT activity was carried out by measuring formation of acetoacetyl-CoA absorption at 313 nm. Protein concentration was measured by Bradford method using bovine serum albumin as a standard substance.

1-4. Identification of Mutation of Protamine-1 and Protamine-2 Genomic DNA

Genomic DNA was isolated from blood by a known method using a protease and phenol. Two kinds of polymerase chain reaction (PCR) primer sets in both of 5′ and 3′ lateral regions were constructed and genomic DNAs of these protamines were amplified. For protamine-1 (Domenjoud, L. et al. (1990) Genomics, 8, 127-133), 24 oligonucleotide (P1A; cccctggcatctataacaggccgc: SEQ ID NO:179) from −42 to −19 upstream from the transcription initiation site was used as the 5′-primer, and 24 oligonucleotide (P1B; tcaagaacaaggagagaagagtgg: SEQ ID NO:180) from 492 to 515 downstream from canonical PolyA addition signal AATAAA was used as the 3′-primer. For protamine-2 (Domenjoud, L. et al. (1990) Genomics, 8, 127-133), PCR amplification was carried out using 24 oligonucleotide (P2A; ctccagggcccactgcagcctcag: SEQ ID NO:181) from +49 to +72 as the 5′-primer, and 24 oligonucleotide (P1B; gaattgctatggcctcacttggtg: SEQ ID NO:182) from 625 to 648 as the 3′-primer. By these primer setting, 557 polynucleotide (SEQ ID NO:170) from −42 to 515 and 599 polynucleotide from 49 to 648 of protamine-1 and protamine-2 genes, respectively can be amplified in the PCR (FIG. 2). PCR conditions were as follows: for protamine-1, 40 cycles of denaturation at 96° C. (45 seconds), annealing at 66° C. (45 seconds), and extension at 72° C. (1 minute) were conducted, and for protamine-2, 40 cycles of denaturation at 98° C. (10 seconds), annealing at 68° C. (45 seconds), and extension at 72° C. (45 seconds) were conducted. The fragments amplified by PCR were purified using SUPREC PCR spin column (Takara, Siga, Japan) and thermal cycle sequence analysis (ABI, CA, USA) was carried out. Determination of DNA sequences was carried out using the same PCR primers.

2. Results

2-1. Sequence Analysis of Human Scot-t DNA

By the PCR primer setting described in the above 1-2, pseudo-gene DNA was not amplified and only true Scot-t genomic DNA was amplified, so that male persons having a risk of infertility and control male persons whose reproducibility was proved were compared.

As a result, four sites of single nucleotide polymorphism: SNP were observed as shown in Table 2. In 516 cases of male persons in total of 255 cases of infertile patients and 261 cases of volunteer persons whose reproducibility was proved, one site was present in the 3′-noncoding region (t1667c), and the other sites were present in the coding region and alterations at 38th, 285th and 352nd amino acids were induced (FIG. 1). With regard to t129c SNP located at 38th amino acid (L38P) within consensus mitochondrial target sequence domain, in reproducible control group and infertile patients, respectively, 94% (246 cases) and 96% (246 cases) were major homozygous leucine type (t/t), 5.4% (14 cases) and 2.7% (7 cases) were heterozygosity (t/c), and 0.4% (1 case) and 0.8% (2 cases) were minor homozygosity, which was observed to cause an amino acid alteration to proline (c/c). With regard to t870g SNP located at 285th amino acid (L285R), in reproducible control group and infertile patients, respectively, 80% (208 cases) and 80% (204 cases) were major homozygous leucine type (t/t), 19% (50 cases) and 15% (39 cases) were heterozygosity (t/g), and 1.1% (3 cases) and 4.7% (12 cases) were SNP minor-type homozygosity (g/g), which was observed to cause an amino acid alteration to arginie (g/g). With regard to c1071t SNP located at 352th amino acid (T352M), in normal control group and infertile male persons, respectively, 96% (250 cases) and 93% (238 cases) were major homozygous leucine type (c/c), 3.1% (8 cases) and 4.3% (11 cases) were heterozygosity (c/t), and 0.8% (2 cases) and 2.4% (6 cases) were minor homozygosity (c/c), which was observed to cause an amino acid alteration from threonine (c/c) to methionine (t/t). With regard to the expression rate of homozygous SNPs causing amino acid alterations at three regions, parent population of infertile patients exhibited significantly two to four times higher value as compared with the value of the reproducible control group. Furthermore, in this case, very interesting SNP (t1667c) was found in the 3′-coding region. In normal control group and infertile male parent population, respectively, 80% (206 cases) and 80% (200 cases) were major t-type homozygosity (t/t), 19% (49 cases) and 15% (38 cases) were heterozygosity (c/t), and 1.2% (3 cases) and 4.8% (12 cases) were c-type minor homozygosity (t/t). All the cases of the minor homozygosity were double SNPs and in both of the normal reproducible control group (3 cases of male persons) and infertile patients (12 cases of male persons), respectively, genotype in t870g was minor g-type homozygosity, but one exception was observed in the infertile cases (the above were shown in Tables 3 and 4). TABLE 3 Background of clinical survey for 255 cases of infertile male persons and mutation in h-Scot-t gene (SNPs) Ratio(%) L38P L285R T352M t1667c Azoospermia 152 (60) 2 6 3  6 Aevere oligospermia  72 (28) 0 5 2  5 Asthenozoospermia  27 (11) 0 1 1  1 Idiopathic infertility  4 (2) 0 0 0  0 255 (100) 2 12 6 12* Reproducible control 261 1 3 2  3** *Total case number: 250 cases (azoospermia 147 cases) **Total case number: 258 cases

TABLE 4 Expression rate of 3 sites of SNPs in coding region and 1 site in non-coding region in infertile and reproductive ability-proved parent populations Increase Type & ratio in position of Geno- Repro-ducible Infertile infertile statistical SNPs type control case case significance t129c t/t 246(94) 246(96) (L38P) t/c  14(5.4)  7(2.7) c/c  1(0.4)  2(0.8) x2 p < 0.54 t870g t/t 208(80) 204(80) (L285) t/g  50(19)  39(15) g/g  3(1.1)  12(4.7) x4 p < 0.018 c1071t c/c 250(96) 238(93) (T352M) c/t  8(3.1)  11(4.3) t/t  2(0.8)  6(2.4) x3 p < 0.17 t1667c t/t 206(80) 200(80) t/c  49(19)  38(15) c/c  3(1.2)  12(4.8) x4 p < 0.018 2-2. Succinyl CoA Transferase Activity of Recombinant h-SCOT-t Having SNPs

In order to investigate influence of SNPs on h-SCOT-t enzyme activity, a recombinant protein having 3 sites of SNPs inducing amino acid replacement was expressed in HEK 293 cell and analysis of succinyl CoA transferase activity was carried out in vitro. All the minor-type SNPs located at t129c (L38P) and c1392t (T352M) exhibited a similar level of enzyme activity to that of major-type SNPs. Contrarily, the minor-type (g/g) SNP located at T870G (L285R) diminished the enzyme activity by half in vitro as compared with the major-type (Table 5). Based on this result, it is shown that the succinyl CoA transferase activity of h-SCOT-t is a prerequisite for male infertility and the SNPs diminishing the enzyme activity contain some cause of male infertility. TABLE 5 Sccinyl CoA transferase activity at inside of HEK 293 cell transformed using recombinant h-Scot-t cDNA having SNPs Major-type L38P L285R T352M Activity ratio 100+− 100+− 50+− 100+− Each assay was conducted three times. 2-3. Sequence Analysis of Human Protamine-1 DNA

A DNA fragment containing 557 bp amplified by PCR contained an intron composed of 91 nucleotides of from 204th to 294th (SEQ ID NO:170, FIG. 2). SNPs in 509 bp within each primer was identified by sequence analysis of a DNA fragment having 557 bp (FIG. 2). Since all DNA samples amplified about the same amount of PCR products, it was confirmed that the SNPs were by no means contained in primer sequence region. The expression rate of SNP was evaluated on male infertile patients as targets, and was compared with the case of volunteers whose reproductive ability was proved. In a total of 528 cases of male subject persons (infertile patients 258 cases and target volunteers having reproductive ability 270 cases), SNPs were found at 5 sites and 4 sites of them were present in the 133th, 160th, 320th and 321st coding region and 1 site was present at 431st of 3′ non-translation region (FIG. 2 and Table 6). All the observed SNPs did not induce alteration of amino acid (silent mutation). All of the 3 sites of SNPs located at a133g, c160g, and g320a and SNP located at 14th and 46th amino acids (FIG. 2) were major homozygosity and heterozygosity and no minor homozygous SNP was observed (Table 6). With regard to the other c321a SNP located at 47th amino acid, in infertile parent population and control parent population having reproductive ability, respectively, 56.6% (146 cases) and 47.8% (129 cases) were homozygous major c/c type, 34.5% (89 cases) and 43.3% (117 cases) were heterozygosity (c/a), and 8.9% (23 cases) and 8.9% (24 cases) were homozygous minor type (a/a) SNP. In addition to a431g SNP in the 3′-non-coding region, all these SNP did not induce any amino acid alteration and also it was not shown that occurrence rate in infertile patients was significantly higher than that in volunteers who were proved to have reproductive ability (Table 6: the positions of nucleotides in Table 6 corresponds to the positions of nucleotides in FIG. 2). TABLE 6 Expression rate of SNPs in protamine-1 and protamine-2 genes in infertile and reproductive ability-proved parent populations Number of SNP (%) Position Reproductive Nucleo- Amino Geno- Infertility ability-proved tide Acid type group control Protamine-1 133 14(R) a/a 250(96.9) 268(99.3) a/g  8(3.1)  2(0.7) 160 23(R) c/c 258(100) 269(99.6) c/a  0(0)  1(0.4) 320 46(R) g/g 257(99.6) 270(100) g/a  1(0.4)  0(0) 321 47(R) c/c 146(56.6) 129(47.8) c/a  89(34.5) 117(43.3) a/a  23(8.9)  24(8.9) 431* a/a 257(99.6) 269(99) a/c  1(0.4)  1(1) Protamine-2 248 50(Q) c/c 257(99.6) 270(100) (Ter)*** c/t  1(0.4)  0(0) 398** g/g 148(57.4) 127(47.0) g/c  88(34.1) 118(43.7) g/a  0(0)  1(0.4) c/c  22(8.5)  24(8.9) 473** a/a 146(56.6) 127(47.0) a/c  90(34.9) 118(43.7) a/c  22(8.5)  25(9.3) Total 258 270 The meanings represented by added asterisk symbol are as follows: *3′-non-coding region **Intron ***Ter: Stop codon (tag) 2-4. Sequence Analysis of Human Protamine-2 DNA

SNPs in 551 bp within each primer were identified by sequence analysis of DNA fragment (SEQ ID NO:173) in 599 bp (FIG. 3). Since all PCR amplified about the same amount of DNA determined on agarose gel electrophoresis, it was confirmed that the primer sequence region did not contain SNPs. In this case, 3 sites of SNPs were observed in 599 nucleotides in protamine-2 gene, and 1 site was present in exon and two sites in intron (FIG. 3). One site of heterozygous SNP in 248th nucleotide changed c into t, which changed glutamine into stop codon. This change was observed only one case of infertile patient among 153 cases of azoospermia patients and also was not found inn 270 cases of reproducible control parent population (Table 6). There is a possibility that this change is associated with a cause of azoospermia even in hemizygous state. Furthermore, 2 sites of SNPs of g398c and a473c were observed within intron. With regard to g398c, in infertile parent population and reproducible control parent population, respectively, 57.4% (148 cases) and 47.0% (127 cases) were major-type homozygosity, 34.1% (88 cases) and 43.7% (118 cases) were heterozygosity (g/c), and 8.5% (22 cases) and 8.9% (24 cases) were minor homozygous (c/c) type. Furthermore, the presence of different heterozygous SNP which was g/a type was observed in 1 case of the control group. With regard to another SNP of a473c, in infertile parent population and reproducible control parent population, respectively, 56.6% (146 cases) and 47.0% (127 cases) were major-type homozygosity, 34.9% (90 cases) and 43.7% (118 cases) were heterozygosity, and 8.5% (22 cases) and 9.3% (25 cases) were c-type minor homozygosity. There was no significant difference in expression rate of these intron SNPs between in the case of infertile parent population and in the case of reproductive ability-proved volunteers.

INDUSTRIAL APPLICABILITY

As precisely described in the above, the invention of this application provides 89 clones of mouse spermatogenesis genes (MSG) and full-length cDNA base sequences of these MSGs. Moreover, the invention provides a method for genetic diagnosis and methods for toxicity test and mutagenicity test using expression modulation and mutation of MSGs as measures. These test methods enable genetic diagnosis directly using male infertility gene DNA and analyses at a molecular level of environmental toxicity as influence of minute amount of chemical substances released into the environment on sexual differentiation and germ cell differentiation and influence of substances having reproduction toxicity and mutagenicity on the living body, especially influence on gene group exhibiting germ cell-specific expression. Furthermore, the invention contributes to detection and measurement of ED having a risk of inducing a low sperm count and reproductive dysfunction as well as global environmental assessment relating to ED. In addition, in the conventional test for “influence on reproduction” purposing detection of teratogenicity, the invention provides an additional novel assay for “mutagenicity against MSGs” and hence remarkably contributes improvement of international standard for assuring safety of medicaments and chemicals.

Moreover, the invention provides Scot-t gene mutation and protamine-2 gene mutation which cause hereditary male infertility. Furthermore, it provides a method for diagnosing male infertility targeting these gene mutations, mutant polypeptides derived from the gene mutations, and the like. 

1. A group of mouse spermatogenesis genes, which is an assembly of 89 genes in total, wherein the respective genes transcribe mRNAs from which cDNAs having the respective base sequences of SEQ ID NOs:1 to 89 are synthesized.
 2. A cDNA library, which consists of cDNAs derived from the respective genes belonging to the group of mouse spermatogenesis genes of claim
 1. 3. A group of DNA fragments each consisting of the base sequence of continuous 10 to 99 bases of the respective cDNAs belonging to the group of cDNA library of claim
 2. 4. A group of primer sets for PCR amplification of DNAs of the respective genes belonging to the group of mouse spermatogenesis genes of claim 1 or the respective cDNAs belonging to the group of cDNAs of claim
 3. 5. A microarray comprising one or more cDNAs belonging to the group of cDNAs of claim 2 or one or more DNA fragments belonging to the group of DNA fragments of claim
 3. 6. A group of mouse spermatogenesis polypeptides, which is an assembly of 78 polypeptides in total, wherein the respective peptides have the respective amino acid sequences of SEQ ID NOs:90 to
 167. 7. A group of antibodies against the respective polypeptides belonging to the group of mouse spermatogenesis polypeptides of claim
 6. 8. A method for assaying toxicity or mutagenicity of a subject substance, which comprising detecting expression modulation or mutation of one or more genes belonging to the group of mouse spermatogenesis genes of claim
 1. 9. A method for diagnosing reproductive ability of a subject individual, which comprises detecting expression modulation or mutation of one or more genes belonging to the group of mouse spermatogenesis genes of claim
 1. 10. A polynucleotide or a complementary sequence thereof, which polynucleotide is complementary to mRNA transcribed from a human male infertility-associated gene Scot-t, and has one or more mutations selected from the following group: “t” at 129th position is replaced by “c”; “t” at 870th position is replaced by “g”; “c” at 1071st position is replaced by “t”; and “t” at 1667th position is replaced by “c”, in the DNA sequence of SEQ ID NO:168.
 11. An oligonucleotide or a complementary sequence thereof, which is part of the polynucleotide of claim 10 and is a DNA sequence consisting of continuous 10 to 99 bases containing the said mutation sites.
 12. A polynucleotide derived from a human chromosomal DNA, which hybridizes the polynucleotide of claim 10 or the oligonucleotide of claim 11 or the complementary sequences thereof under a stringent condition.
 13. A primer set for PCR amplification of the polynucleotide of claim 10, the polynucleotide of claim 12, or mRNA transcribed from the polynucleotide of claim 12, wherein one of the primers is an oligonucleotide or a complementary sequence thereof which is a DNA sequence consisting of continuous 15 to 45 bases containing the mutation site.
 14. A polynucleotide or a complementary sequence thereof, which polunucleotide is complementary to mRNA transcribed from a human male infertility-associated gene protamine-2, and “c” at 248th position is replaced by “t” in the DNA sequence of SEQ ID NO:173.
 15. An oligonucleotide or a complementary sequence thereof, which is part of the polynucleotide of claim 14 and is a DNA sequence consisting of continuous 10 to 99 bases containing the mutation site.
 16. A polynucleotide derived from a human chromosomal DNA, which hybridizes the polynucleotide of claim 14 or the oligonucleotide of claim 15 or the complementary sequences thereof under a stringent condition.
 17. A primer set for PCR amplification of the polynucleotide of claim 14, the polynucleotide of claim 16, or mRNA transcribed from the polynucleotide of claim 16, wherein one of the primers is an oligonucleotide or a complementary sequence thereof which is a DNA sequence consisting of continuous 15 to 45 bases containing the mutation site.
 18. A polypeptide, an expression product of the polynucleotide of claim 10 or 12, which has one or more mutations selected from the following group: Leu at 38th position is replaced by Pro; Leu at 285th position is replaced by Arg; and Thr at 352nd position is replaced by Met, in the amino acid sequence of SEQ ID NO:169.
 19. A polypeptide, an expression product of the polynucleotide of claim 14 or 16, which consists of the amino acid sequence of 1st to 49th positions of the amino acid sequence of SEQ ID NO:174.
 20. An oligopeptide, which is a part of the polypeptide of claim 18 and is an amino acids sequence consisting of continuous 5 to 30 amino acids containing the mutation site.
 21. An oligopeptide, which is part of the polypeptide of claim 19 and is an amino acid sequence consisting of continuous 5 to 30 amino acids.
 22. An antibody prepared using the oligopeptide of claim 20 as an antigen.
 23. An antibody prepared using the oligopeptide of claim 21 as an antigen.
 24. An antibody prepared using the oligopeptide consisting of the amino acid sequence of 50th to 91st positions of SEQ ID NO:174 or the amino acid sequence of 1st to 11th positions of SEQ ID NO:175 as an antigen.
 25. A method for diagnosing male infertility, which comprises detecting presence of the polynucleotide of claim 12 or 16 in a chromosomal DNA isolated from a subject person.
 26. The method according to claim 25, which comprises detecting whether a chromosomal DNA or an mRNA thereof isolated from a subject person hybridizes the polynucleotide of claim 10 or 14 or the oligonucleotide of claim 11 or 15, or the complimentary sequences thereof under a stringent condition or not.
 27. The method according to claim 25, which comprises detecting presence of a PCR product when PCR is carried out using a chromosomal DNA or mRNA isolated from a subject person as a template with the primer set of claim 13 or
 17. 28. A method for diagnosing male infertility, which comprises detecting presence of the polynucleotide of claim 18 or 16 in a biological sample isolated from a subject person.
 29. The method according to claim 28, which comprises detecting presence of a polypeptide reactive to the antibody of claim 22 in a biological sample isolated from a subject person.
 30. The method according to claim 28, which comprises detecting presence of a polypeptide, which is reactive to the antibody of claim 23 but not reactive to the antibody of claim 24, in a biological sample isolated from a subject person.
 31. A DNA probe, which is a labeled oligonucleotide of claim 11 or
 15. 32. A DNA chip comprising the oligonucleotide of claim 11 and/or claim
 15. 33. A labeled antibody, wherein the antibody of claim 22, 23 or 24 is labeled. 